Towards a long-term strategy for reducing carbon dioxide emissions ...
Towards a long-term strategy for reducing carbon dioxide emissions from our housing stock
Executive summary The United Kingdom has a goal of reducing its
that there is only a small number of ways to
overall carbon dioxide (CO2) emissions by 60 per
reach a 60 per cent - 80 per cent reduction in
cent by 2050, and this figure may well increase
emissions. This report shows that we can
to 80 per cent. It is likely that we will need to
achieve, with today’s technologies, and without
achieve this level of reduction from our housing
any improvements in appliance use, the
stock. This is because there is a high potential
following:
for sustainable energy measures in housing, many of which are cost-effective even today. The necessary measures will not actually be installed as a matter of course. They need a variety of support, including regulation, promotion, and supply chain development. Some of this may entail politically difficult
16 per cent reductions from installing all energy efficiency measures at current grid carbon intensity. 25 per cent reductions from simply installing currently cost-effective measures and median decarbonisation of the grid.
decisions, active changes in behaviour and
50 per cent reductions if we “throw
attitude, and upfront, long-term industry
everything” at the housing stock, both
investment. In order to justify and give context
insulation and microgeneration, and implement
to such changes, there is a need for a strategy
a programme of behaviour change, at current
for the improvement of the housing stock to
grid intensity.
2050.
68 per cent reductions from “throwing
Such a strategy needs to identify the total
everything” at the housing stock together with
potential for measures to reduce emissions.
a programme of behaviour change, and
And it needs to identify the least-cost route to
achieving a median decarbonisation of the grid
securing these. It is important to understand
(see figure).
Figure: “Throwing everything at the housing stock,” together with programme of behaviour change, and median decarbonisation of the grid
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
Year
4
2037
2042
2047
The benefits of using trigger points 1. The householder is already thinking of undertaking works, so is receptive to ideas. 2. Workmen may already be on site, so there is little additional disruption and hassle. 3. There is scope to incorporate improvements, that will be lost once the works are complete. 4. The cost of improvement work may be less as workmen, scaffolding, etc. are already on site. 5. There is the potential to regulate and enforce, rather than relying purely on marketing.
Notable trigger points with potential include: moving home
change of tenancy
reroofing
new windows
extension
loft conversion
scaffolding
new kitchen
new bathroom
reflooring
Even more can be achieved towards or beyond an 80 per cent reduction with initiatives to reduce appliance usage, although these have not been investigated here. Likewise, new technologies with better performances are likely to become available between now and 2050 but are also outside the scope of this
new heating system
Recommendations The report sets out what is technically possible, and the contribution of various policies towards achieving this. In this context, the Energy Saving Trust would like to see: •
A long-term target of 80 per cent by 2050, together with interim targets, for emission
report.
reductions from the housing stock
The report also shows that we can accelerate the uptake of a variety of measures, and
large-scale refurbishment
•
A programme of public engagement to
achieve additional savings, by taking advantage
help gain buy-in into the technologies and
of the naturally occurring opportunities for
policies required to effect the emissions
improvement – “trigger points” – over the
reductions required.
course of the lifetime of each and every home.
•
Building Regulations (2010) to extend
Improvements can often be effected at these
coverage of triggers for improving the
points far more easily than at other times.
energy performance of existing homes,
The significance and importance of such trigger
including extensions, loft conversions, etc.
points can only be fully understood, and
•
A signal that the recommendations of
therefore action justified in relation to them, if
Energy Performance Certificates will
they are seen in the context of a long-term
become mandatory by a certain date in the
strategy. It is hoped that this report from the
future, say 2015, for home sales, rental,
Energy Saving Trust provides such context.
etc. •
A variety of incentives and awareness raising activities, developed around people’s behaviour and the lifetime of their homes, in preparation for eventual mandation.
5
These recommendations can be taken forward
•
now. As set out earlier, there is only a small number of ways to reach a radical reduction in emissions from the housing stock, and the
and lighting usage. •
impact of keeping temperatures at today’s
these. There are, of course, uncertainties: the
levels).
future cost of technologies; the emergence of •
Introduction of energy price projections and associated fuel bill savings and paybacks.
name but a few. We cannot however wait until these uncertainties are resolved. This is not only
Impact of behavioural campaign for optimum usage of home (beyond modelled
recommendations are consistent with all of
new technologies; and grid carbon content to
Impact of measures to reduce appliance
•
because we have national and international
Impact of policies on the EPC rating profile (A-G) of the housing stock.
obligations to meet interim carbon reduction targets; but because unless we press ahead, encouraging behavioural change and investment in new technologies, we will both miss existing opportunities and fail to open up
2. Further work expanding on the model: •
implemented as part of wider works.
new ones. A long-term strategy, the development of immediate policies and the
•
•
Impact of various levels of incentive and encouragement before mandation, building
Further work
on the Energy Saving Trust consumer
There are a number of further areas that could Saving Trust’s work to date including:
Capital cost reductions with time and with volume installations.
provision of policy signals, are needed now.
usefully be looked into, building on the Energy
Marginal capital cost when measures are
segmentation model. •
New technologies and improved technology performance.
The Energy Saving Trust will consider which of 1. Further exploration of the model: •
Impact of proliferation of domestic air conditioning, and measures to counter this.
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these to take forward, depending on interest and resource availability.
Introduction In 2006 the Energy Saving Trust made a
The report is based on a model of CO2
submission to Government as part of the Review
emissions from the housing stock, produced for
of the Sustainability of Existing Buildings. The
the Energy Saving Trust by Element Energy Ltd.
submission recommended the development of a
The model focuses on improving the fabric and
long-term strategy for reducing CO2 emissions
services of the home, although it does allow
from the housing stock by 2050. The reduction
for some behavioural change and for variations
proposed was 60 per cent, the Government’s
in appliance energy use.
long-term goal for overall CO2 emissions
The report sets out the Energy Saving Trust’s
reductions, although the Energy Saving Trust
conclusions drawn from the model. However, it
supports moves to revise this to 80 per cent.
is hoped that Government and other
This report sets out in more detail the
stakeholders will engage in debate and will
importance of having such a strategy. In
make use of this and other models, to develop
particular, it focuses on the opportunities for
a strategy and much needed policies for the
improving the energy performance of homes -
long-term improvement of the housing stock.
opportunities that occur naturally over the lifetime of these homes but that are in the main currently being missed. The report looks
CO2 emissions targets
at how these opportunities could be grasped,
The United Kingdom has a goal of reducing its
and the impact on long-term CO2 emissions
overall CO2 emissions by 60 per cent by 2050.
from the housing stock.
The Climate Change Bill 2008 anticipates the
The report has been produced in the context of
setting of a reduction target of 26-32 per cent on
a number of seminal publications in this area,
1990 emission levels by 2020, and 60 per cent by
notably: “Reducing Carbon Emissions from the
2050, with the possibility of this being raised to
UK Housing Stock” (BRE), “Stock Take” (SDC),
80 per cent in view of emerging climate change
“40 per cent House,” “Home Truths” (both by
science. These targets will be enshrined in
ECI), and most recently, “How Low” (WWF).
legislation.
What the Energy Saving Trust wishes to add to
It is likely that we will need to achieve these levels
the agenda is the consideration of using
of reduction from our housing stock. This is
naturally occurring opportunities as “trigger
because there is a high potential for sustainable
points” for implementing the housing
energy measures in housing, many of which are
improvements discussed in all of these
cost-effective even today. Indeed, other sectors
publications.
may be more difficult or costly to tackle.
1
However, emissions from the housing stock are reducing very slowly, as shown in figure 1:
1 Full references: “Reducing Carbon Emissions from the UK Housing Stock,” BRE for DEFRA, 2005; “Stock Take: Delivering Improvements in Existing Housing”, Sustainable Development Commission, 2006; “40% House,” Environmental Change Institute, February 2005; and “Home Truths - A Low-Carbon Strategy to Reduce UK Housing Emissions by 80% by 2050,” Environmental Change Institute, November 2007; “How Low – Achieving Optimal Carbon Savings from the UK’s Existing Housing Stock,” WWF-UK, 2008.
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Figure 1: CO2 emissions from the UK housing stock 60
Million tonnes of carbon
50 Oil
40
Electric Gas
30
Solid
20 10 0 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Year
BRE March 2008
Note vertical axis is MtC, not MtC02 as used in later graphs
In fact, assuming current trends in energy
Even assuming: a) ongoing uptake of cost-
efficiency improvements and grid carbon intensity
effective energy efficiency measures under the
(relatively static), we would have a significant
Carbon Emissions Reduction Target (CERT),2 and
increase in CO2 emissions by 2050. This upward
b) the achievement of the 2016 zero-carbon
trend is the result of increasing internal
target for newbuild housing not only in England
temperatures, increasing appliance usage, and
but across the UK, our emissions by 2050 would
increasing number of homes.
be more or less back up to their current levels:
Figure 2: Long-term emissions at current grid intensity, ongoing uptake of energy efficiency at CERT levels, and achievement of 2016 zero-carbon newbuild target
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions. 2 CERT targets account for the majority of cost-effective energy efficiency installations in existing housing. It is assumed here that the suppliers obligation will continue at a similar level to CERT.
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It is possible that the grid will decarbonise
does not achieve the reductions we need;
significantly by 2050, say to 50 per cent of
third, grid decarbonisation is not guaranteed to
today’s carbon content. Together with the
happen, and fourth, simply presenting
assumptions above on accelerated uptake of
“upstream” solutions does not lead to
energy efficiency and achievement of the 2016
behavioural and culture change on wider
newbuild target, this would reduce our CO2
sustainability, and at best will turn out to be an
emissions by some 20 per cent as shown in
interim fix.
figure 3.
For all these reasons, the Energy Saving Trust
However, we cannot rely solely on such grid
believes a coherent range of housing related
decarbonisation; first, if we use clean energy
policies is needed if we are to ensure successful
inefficiently, we will need a lot more of it;
achievement of our 2050 target.
second, moderate grid decarbonisation alone
Figure 3: Long-term emissions at reduced grid intensity, ongoing uptake of energy efficiency at CERT levels, and achievement of 2016 zero-carbon newbuild target
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
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The need for a clear strategy
The longer we leave it, the steeper the reductions curve. This is not only because we
It has been shown that much more is needed to move us away from the “business-as-usual” trajectory of CO2 emissions. Action is
will have less time to reach the same target, but also in physical terms (even if not in terms of conventional thinking on targets) because
needed both on newbuild and on existing housing. It needs to be recognised that the less we do on one, the more we must do on the
we must compensate for the additional emissions that have accumulated in the atmosphere in the intervening period. So a
other.
linear 60 per cent goal set in 2000 actually
The action necessary may include upfront
corresponds to a roughly 75 per cent linear
investment or politically difficult decisions such
goal if started in 2010, and the same goes for
as stronger regulatory requirements. In order to
the impact of delaying the introduction of
justify difficult decisions, effect culture change,
action towards a possible 80 per cent reduction
and secure long-term industry investment, we
target.
need to have a long-term strategy.
Figure 4: Indicative emissions profile from new and existing housing to achieve 80% reduction
45 Total CO2 emissions on 2005 baseline
40 35 30 25 20 15 10 new
5 0 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
existing
Year
*Note vertical axis is MtC, not MtCO2 as used in later graphs.
10
Figure 5: CO2 emissions trajectories for equivalent amounts of accumulated atmospheric carbon
Percentage of 2000 CO2 emissions
120 100 60 60 40 20 0 2000
2010
2020
2030
2040
2050
Year
The model The model used for this report is based on EHCS data, aggregated up to UK household numbers. It can be adapted to accommodate the specific needs of the Devolved Administrations. We believe what is new about the model as a tool is that it is sufficiently versatile to simulate a range of policies, and packages of sustainable energy measures, to improve the housing stock over the course of time from the present to 2050. It allows the setting of policies that trigger various improvements at certain points over the lifetime of the property. The model assumes a baseline trend consistent with anticipated activity under the Carbon Emissions Reduction Target (CERT) followed by the supplier obligation at a similar level, and the impact of further policies is assessed against this. The model focuses on the house itself. Domestic air conditioning can be modelled, though it has not been investigated in this report. Appliance emissions are included, but are not disaggregated by type of appliance. This can be done as follow-on work if needed. Further
developmental work would be needed to model the impact of new, as yet unspecified technologies, and of a behavioural campaign for optimum usage of the home (beyond the modelled impact of keeping temperatures at today’s levels). Further detail on the model is provided in Appendix A.
The potential for improvements to the housing stock We can reduce CO2 emissions associated with buildings (i.e. space heating, water heating, and lighting) by over 60 per cent and more in many homes today, using existing technologies and without resorting to full-on microgeneration. This can be done through a combination of:3 •
installing all the cost-effective insulation measures
•
internally or externally cladding non-cavity walls
•
upgrading the heating system
•
adding solar thermal water heating.
3 See:“Refurbishing Dwellings – A Summary of Best Practice,” Energy Saving Trust, 2007, for an illustration of savings and how these can be made.
11
This is shown for a common, Victorian terraced property: Figure 6: The contribution of individual measures to a 60% reduction in emissions kg/CO2/m2/yr 70 60
59.1
58.1
55.8
50 40.4
40
34.1
31.9
30
22.2
20
19.8
10 0
Base
100% low energy lights
Floor (0.17)
Walls (0.30)
Windows (1.5) and draughtproof
Roof (0.16)
Solar Heating thermal (91% condensing (4m2) with controls
Energy Saving Trust Best Practice programme
The relative contribution of wall insulation
Because many solid walled homes are long,
should not be underestimated. Objections to
or deep, the front wall can be internally
the insulation of non-cavity walls on the basis
insulated without significant relative loss of
of aesthetics need to be addressed, but are not
floor area.
necessarily insurmountable: •
•
Additional microgeneration measures, for
The back and sides of solid-walled homes
example, biomass boilers, heat pumps, can
can generally be insulated externally with
then reduce the emissions from the home
little negative effect on overall aesthetics.
still further.
The front façade forms a relatively low proportion of surface area on many solidwalled homes.
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•
The impact of applying the full range of energy
These technical improvements can be
efficiency and a wide range of microgeneration
enhanced by a national campaign to keep
measures universally, compared with an
average internal temperatures at their current
otherwise upwards trend in CO2 emissions, is
level of 18oC, delivering still more carbon
shown in figure 7 to result in over 40 per cent
reductions, almost 50 per cent, as shown in
carbon emission reductions.
figure 8.
Figure 7: Comprehensive energy efficiency and microgeneration measures applied to all homes4
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027 2032 Year
2037
2042
2047
See Appendix for full set of assumptions.
Figure 8: Comprehensive energy efficiency and microgeneration measures applied to all homes together with behavioural campaign5
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2042
2047
Year See Appendix for full set of assumptions.
4 Under this scenario, all homes are internally or externally insulated and 50% of homes have biomass boilers. There is little benefit in converting gas heated homes to heat pumps at current grid intensity. 50% of flats are converted to biomass CHP. 5 Assumes that internal temperatures remain constant at 2007 levels.
13
This highlights the importance and value of
hot water usage, turning off lights and
engaging people and encouraging changes
appliances.
in attitude and behaviour, not just focusing solely on technical solutions. In fact, there are still more savings likely to be had through optimum use of the home beyond
Pure energy efficiency measures, i.e. the above scenario without microgeneration, would deliver some 16 per cent reductions:
keeping temperatures constant – for
Utilising only the cost-effective energy efficiency
example, switching heating off when not
measures would fall well short of our target,
needed, better zoning of heating, prudent
and not deliver the step change that is needed:
Figure 9: Comprehensive energy efficiency measures applied to all homes
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
14
Figure 10: Comprehensive cost-effective energy efficiency measures only, applied to all homes
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This highlights the need for focused activity to
grid, relying solely on the above cost-effective
bring further, currently more expensive
measures and not investing in further housing
measures on stream, and to create market
improvement measures would fall well short of
demand for these.
our target, achieving only a 25 per cent
Even with halving of the carbon intensity of the
reduction in CO2 emissions as shown below.
Figure 11: Comprehensive cost-effective energy efficiency measures applied to all homes, together with grid decarbonisation
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2032
2047
Year See Appendix for full set of assumptions.
15
Figure 12: Comprehensive energy efficiency and microgeneration measures applied to all homes, together with behavioural campaign and grid decarbonisation6
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2032
2047
Year See Appendix for full set of assumptions.
However, as shown in figure 12, if we applied
driven - in terms of public opinion, local
all household measures, and behavioural
opposition, and Ministerial inclination. As such,
measures, together with grid decarbonisation,
reliance solely on future decisions for a low-
then we are verging on a 70 per cent reduction
carbon grid is risky. Furthermore, in the event
in CO2 emissions:
that we are off target or need to achieve more,
What these figures show is that there is only a small number of ways to reach a 60 per cent-80
it is difficult to fine-tune grid intensity, given the timescales for making investment decisions.
per cent reduction in emissions from the
External cladding can also be a controversial
housing stock. And that for those that do
measure, for two reasons:
achieve this, energy efficiency, microgeneration, consumer attitudes and grid decarbonisation all
•
looking properties.
need to be aligned, in roughly equal measure. There is no point in waiting to see which is
It is generally opposed on traditional
•
It may not fit in with the local vernacular, even if this is not “traditional.”
“better.” All are needed.
Therefore there would need to be public Risks and sensitivities Decisions on investments in power generation
engagement and an area-based approach if this measure was to form a significant part of the strategy.
can be highly controversial and politically
6 This scenario entails 50% of homes with biomass boilers and 50% with heat pumps. – Once the grid carbon intensity begins to drop, it begins to make carbon-sense to replace gas heating with heat pumps.
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In economic theory, it makes sense to wait for
order for householders to be receptive to CERT
the cost of technologies to come down and for
offers; b) many householders simply do not
other uncertainties likewise to be resolved.
trust their energy supplier to offer them energy
However, in practice, industry capacity issues
saving measures; c) CERT does not have an
are of crucial importance. The earlier industry
absolute carbon cap and it is uncertain how
can be geared up, the less of a step-change is
the provision for influencing consumer
required and the more realistic it is to achieve
behaviour will be used; and d) CERT does not
the target.
take a strategic, market transformation
Politically also, we are obliged both to meet
approach to particular technologies.7
international targets, and to show leadership
In short, energy supplier activity is a very
on the world stage by delivering emissions
important part of a housing improvement
reductions now, not just promising them for
strategy – but it is not a housing improvement
the future. Having said that, we need to meet
strategy itself, and this is what is needed.
our interim targets without jeopardising our long-term strategy.
The most effective point at which to ensure the necessary measures are installed is often when the householder is already thinking of
The policies for improvements Clearly, CERT will achieve a significant improvement in the uptake of cost-effective measures. However, even if we increase the CERT target under the Supplier’s Obligation, some housing simply will not be addressed.
undertaking works, or is indeed doing so. There is an argument that requiring additional sustainable energy measures at the time of works will simply discourage people from having such works done in the first place. This issue needs to be addressed with appropriate incentives and enforcement. There are parallels
We cannot solely rely on CERT because, despite
with minimum standards, and indeed health
its undoubted effectiveness, it has a number of
and safety regulations in any field, which is not
limitations. These have been shown to be as
a reason not to introduce these.
follows: a) there is a need for awareness raising and the provision of impartial information in
The benefits of using trigger points 1. The householder is already thinking of undertaking works, so is receptive to ideas. 2. Workmen may already be on site, so there is little additional disruption and hassle. 3. There is scope to incorporate improvements, that will be lost once the works are complete. 4. The cost of improvement work may be less as workmen, scaffolding, etc. are already on site. 5. There is the potential to regulate and enforce, rather than relying purely on marketing.
7 See Energy Efficiency Innovation Review, Defra, 2005.
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The policies modelled in this report feed off a
We also need to consider what happens over
number of “trigger points” over the lifetime of
the lifetime of a home in each sector as shown
the housing stock. This means looking at the
in figure 14.
breakdown of our housing stock as shown in figure 13.
Figure 13: Indicative breakdown of housing stock to 2050 Projection of UK housing stock: by tenure 40 35
Houses (millions)
30
Post 2007: Social
25
Post 207: Private rented
20
Post 2007: Owner occupied
15
Pre 2007: Social 10
Pre 2007: Private rented
5 0 2006 2010 2014 2018 2022 2026 2030 2034 2038 2042 2046 2050
Pre 2007: Owner occupied
Year
Figure 14: Opportunities for effecting improvements over the lifetime of a home
100%
Boiler replacement Home moving
Reroofing Extension built
tC/yr
Window replacement Change in energy supplier
New heating system Conversion to flats 20%
2005
18
Year
2050
We then need to take advantage of each of
It is important furthermore to view the
these trigger points by establishing a
trajectories in the context of an ongoing
mechanism for ensuring that they lead to
programme of energy supplier targets, i.e.
improvements in energy performance.
CERT, followed by the Supplier Obligation. The
A number of scenarios are modelled in the following. These scenarios describe the carbon impact of utilising various trigger points. They do not describe the policy mechanism itself, which may be a combination of regulation, awareness raising, supply chain capacity, and grant support. This is consistent with the aim of this report, which is to set out what needs
emissions reductions associated with the scenarios proposed could be considered as additional to energy supplier activity; or they could be considered as simply absorbed within the setting of higher energy supplier targets in years to come. Either way, it is clear that without the policies set out below, obvious opportunities to save carbon will be lost.
to happen, thereby giving a clear framework
This scenario entails a requirement that all the
for Government to introduce the appropriate
currently cost-effective recommendations of
mix of policies.
Energy Performance Certificates be
The carbon emission trajectories are set out individually for each scenario. They cannot
implemented upon the sale of a home, from some point in the future, say 2010.
simply be added, because there are inter-
The scenario brings forward the installation of
relationships. For example, if it is mandatory to
cost-effective measures, ensuring that we meet
install all EPC recommendations when
interim targets and pave the way for further
refurbishing a home, then there are no further
measures in the future. An additional 5MtCO2
savings to be had when selling that home, even
(3.5 per cent) would be saved over the course
if implementation of EPC recommendations is
of the decade.
again mandatory at that point.
Figure 15: All cost-effective recommendations of EPC mandatory upon home sale
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year
19
Figure 16: All cost-effective recommendations of EPC mandatory upon home sale, including advanced measures from 2020.
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
Whilst mandation may be politically
internal or external wall insulation and of
contentious in the short term, plenty of
advanced glazing will have reduced somewhat,
advance warning, together with a mix of
and that there will be public acceptance of the
incentives to improve the home in the
requirement to install more expensive measures
intervening period, would seem to be a fair
in the interests of climate change mitigation.
way of presenting such a policy to the British
These measures will therefore also be
public.
mandated upon home sale by 2020.
As shown above, this scenario builds on the
The scenario begins to make inroads into long-
policy of mandatory implementation of cost-
term carbon emission reductions, saving some
effective EPC recommendations upon home
20MtCO2 (15 per cent) by 2050.
sale. It assumes that, by 2020, the cost of
20
Figure 17: All cost-effective recommendations of EPC mandatory upon building of extension. 145
CO2 emissions (millions tonnes)
140 135 130 125 120 115 110 105 100 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails a requirement that all the
The rationale for this policy is that, if a
currently cost-effective recommendations of an
householder is increasing their carbon footprint
Energy Performance Certificate are
by building an extension, it seems only
implemented for the whole home, when an
fair that they install the cost-
extension is built.
effective measures, in the
Whilst the contribution is small in immediate carbon terms, “consequential improvements” are a useful mechanism for triggering necessary and fair improvements, and can be
rest of their home in order to compensate at least to some degree.
built on with time. Note that in an
It should also
environment where housebuilding and house
be noted that
sales are declining, it is likely that the number
the changes
of extensions, and therefore the carbon
will benefit the
footprint associated with extensions, will
householder.
increase.
This scenario
21
Figure 18: All cost-effective recommendations of EPC mandatory upon building of extension, including advanced measures from 2020. 145
CO2 emissions (millions tonnes)
140 135 130 125 120 115 110 105 100 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
builds on the policy of mandatory implementation of cost-effective EPC recommendations upon the building of an extension. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of measures such as internal or external wall insulation, and advanced glazing, when householders wish to increase their carbon footprint by building an extension. The impact of “consequential improvements” with the inclusion of these measures amounts to almost 3MtCO2 (two per cent) savings by 2050.
22
Figure 19 All cost-effective recommendations of EPC mandatory upon major refurbishment of a home (7 year refurbishment cycle assumed)
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027 Year
2037
2047
See Appendix for full set of assumptions.
This scenario entails a requirement that all costeffective recommendations of an EPC be implemented upon major refurbishment of a home or estate or block of flats. Seven years is the average tenure of owner-occupied property, and is also an indicative maintenance schedule (including property management contracts) for many managed buildings. When a home is in any case being refurbished, implementing the EPC recommendations would seem an opportune time, leading to reasonable carbon savings. The resultant savings are particularly notable in the shortmedium term, i.e. some 12MtCO2 by 2016, and therefore useful for meeting interim
climate change targets. The savings by 2050 are 6MtCO2 (four per cent). Note that such a cycle of improvements could be mandated in the social sector relatively easily. This scenario builds on the policy of mandatory implementation of cost-effective EPC recommendations upon major refurbishment. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of internal or external wall insulation and of advanced glazing. The impact of this policy amounts to emissions reductions of 20MtCO2 (15 per cent).
Figure 20: All cost-effective recommendations of EPC mandatory upon major refurbishment of a home (7 year refurbishment cycle assumed), with advanced measures from 2020 CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027 Year
2037
2047
See Appendix for full set of assumptions.
23
Figure 21: All cost-effective recommendations of EPC mandatory upon change of tenancy
CO2 emissions (millions tonnes)
17 16 15 14 13 12 11 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails a requirement to
The impact on the private rented sector of
implement all cost-effective recommendations
mandatory EPC implementation upon change
arising from the EPC before letting the
of tenancy is significant in the short-medium
property. Note that the production of an EPC is
term, at over 0.5MtCO2 (three per cent) for
mandatory for all new tenancies from October
that sector alone (only 12 per cent of the
2008.
stock) by 2016. This is helpful for reaching interim climate change targets, and also paves the way for mandating larger interventions further down the line. The policy of ensuring basic energy efficiency measures are installed in rented accommodation might furthermore be consistent with the need to raise living standards in this sector and protect low-income tenants from undue fuel poverty.
24
Figure 22: All cost-effective recommendations of EPC mandatory upon change of tenancy, including advanced measures from 2020 18
CO2 emissions (millions tonnes)
16 14 12 10 8 6 4 2 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario builds on the policy of mandatory implementation of of all cost-effective recommendations outlined in the EPC upon change of tenancy. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of internal or external wall insulation and of advanced glazing upon change of tenancy. The savings from more advanced measures upon change of tenancy are substantial, at 4MtCO2 (25 per cent private rented sector emissions).
25
Figure 23: Mandatory solar panels (50% solar thermal, 50% PV) upon re-roofing.
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
26
This trigger point policy focuses on one
amount to 4MtCO2 (three per cent) by 2050.
particular part of the building, i.e: the roof,
Furthermore, the proliferation of solar panels
rather than the whole EPC. It requires that
through this mechanism would facilitate wider
either a photovoltaic array or a solar thermal
market transformation by fostering
system is installed upon re-roofing, and
acceptability and desirability of these
assumes a 50:50 uptake. Carbon savings
technologies.
Figure 24: All window replacements advanced glazing from 2016
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This trigger point policy focuses on another
The cost today would be high, but a signal that
part of the building, i.e. the window, in the
such a policy was forthcoming would secure
form of a minimum standard for replacement
ongoing industry investment and drive costs
products. It requires that every window
down, not to mention the development of new
replaced from 2016 onwards is triple glazed.
products.
The saving to 2050 is 2MtCO2 (1.5 per cent).
27
Figure 25: Replacement of coal/oil fuelled heating systems with biomass heating, together with gas condensing boilers replacing electric heating
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails the mandatory
this if grid carbon intensity remains at current
replacement of the worst polluting forms of
levels. Clearly, where there is no gas, other
heating with less carbon-intensive systems.
options for the replacement of electric systems
Coal/oil fuelled heating are replaced with
would need to be looked at.
biomass boilers, and electric heating is replaced with gas condensing boilers, upon the end of the life of the existing heating systems.
heating systems are substantial at 6MtCO2 (four per cent) by 2050. The necessary volume
Note that, in a median grid scenario, the
and supply chain for biomass fuel would also
electric heating might be replaced with a heat
need to be secured.
pump, but there is little carbon-sense in doing
28
The savings from replacing the worst polluting
Next steps Each of the above scenarios needs the detailed development of policy mechanisms to ensure that they are delivered. What is crucial to note
1. Further exploration of the model: •
conditioning, and measures to counter this.
is that the scenarios show ‘what’ needs to be achieved. We look forward to working with
•
Impact of measures to reduce appliance and lighting usage.
Government and other stakeholders on how this can be done, in the knowledge of the
Impact of proliferation of domestic air
•
Impact of behavioural campaign for
desired outcome.
optimum usage of home (beyond modelled
Key elements of activity the Energy Saving Trust
impact of keeping temperatures at today’s
would like to see are the development of:
levels).
•
A long-term target of 80 per cent by 2050,
•
associated fuel bill savings and paybacks.
together with interim targets, for emission reductions from the housing stock. •
Introduction of energy price projections and
•
Impact of policies on the EPC rating profile (A-G) of the housing stock.
A programme of public engagement to help gain buy-in into the technologies and policies required to effect the emission reductions required.
•
Building Regulations (2010) to extend
2. Further work expanding on the model: •
implemented as part of wider works.
coverage of triggers for improving the energy performance of existing homes,
•
including extensions, loft conversions, etc. •
A signal that the recommendations of
Capital cost reductions with time and with volume installations.
•
Impact of various levels of incentive and
Energy Performance Certificates will
encouragement before mandation, building
become mandatory by a certain date in the
on Energy Saving Trust consumer
future, say 2015, for home sales, rental,
segmentation model.
etc. •
Marginal capital cost when measures are
A variety of incentives and awareness raising activities, developed around people’s behaviour and the lifetime of their homes, in preparation for eventual mandation.
•
New technologies and improved technology performance.
The Energy Saving Trust will consider which of these to take forward, depending on interest and resource availability.
In addition, there are a number of further areas that could usefully be looked into, building on the Energy Saving Trust’s work to date. These are as follows:
29
Appendix A: Summary of the model The model used for this report is based on
A comprehensive range of microgeneration
EHCS data, aggregated up to UK household
technologies and building fabric measures is
numbers. It can be adapted to accommodate
included in the model. A housing stock model
the specific needs of the Devolved
is maintained for each year, from 2007 to
Administrations. Based upon an analysis of
2050, which includes data on technology
house condition survey data, the housing stock
lifetime and replacement rates. By applying
is reduced to 82 distinct housing types which,
these measures to appropriate houses, the
when added together, are representative of the
model is able to predict CO2 emissions from
stock as a whole.
each house type, and therefore from the
The factors delineating different house types
complete housing stock.
are: age of house (three age ranges); tenure
We believe what is new about the model as a
(owner-occupier, private-rented, social); heating
tool is that it is sufficiently versatile to simulate
fuel type (natural gas, electricity, oil,
a range of policies, and packages of
community heating, coal); size (small – flats,
sustainable energy measures, to improve the
medium – terraced houses, and large –
housing stock over the course of time from the
semi/fully detached); and condition (poor and
present to 2050. It allows the setting of
good). New house types are represented by 33
policies that trigger various improvements at
distinct house models.
certain points over the lifetime of the property.
Each of these house types has distinct settings
The model focuses on the house itself.
within an energy model, based on the
Domestic air conditioning can be modelled,
Standard Assessment Procedure (SAP) for
though it has not been investigated in this
thermal loads, and BREDEM for consumer
report. Appliance emissions are included, but
electrical loads. The model predicts energy
are not disaggregated by type of appliance.
consumption and CO2 emissions from each
This can be done as follow-on work if needed.
housing sector, and from the whole stock. UK
Further developmental work would be needed
domestic energy consumption predictions
to model the impact of new, as yet unspecified
from this model are calibrated against DUKES
technologies, and of a behavioural campaign
2007 data.
for optimum usage of the home (beyond the modelled impact of keeping temperatures at today’s levels).
30
Appendix B: Assumptions Baseline The baseline assumptions for all figures in this report are as follows: •
•
Comprehensive energy efficiency measures means all the currently available fabric and heating measures. This includes both the costeffective measures, and the more expensive
High grid carbon intensity at current levels,
measures such as internal or external wall
and constant until 2050.
insulation and advanced glazing (triple glazing
Achievement of zero-carbon newbuild
is modelled for this). It is of course recognised
policy from 2017 onwards across the UK.
that new and improved energy efficiency products will emerge with time, so a scenario
•
Internal household temperatures rise linearly from 18oC to 22oC by 2050.
cannot be truly comprehensive. Advanced energy efficiency measures mean
•
Ongoing CERT rates of uptake of basic energy efficiency measures until saturation.
•
those that are not currently staple, costeffective measures, i.e. internal/external wall
One per cent p.a. ongoing increase in
insulation and advanced glazing. It is
energy consumption of domestic
acknowledged that there are many more
appliances.
“advanced” or innovative measures.
The impact of all scenarios and policies is
Comprehensive microgeneration measures
assessed against this baseline.
means every roof having a PV or solar thermal system, and all heating replaced by either biomass or heat pumps. With a high-grid
Saturation scenarios
scenario, it makes little carbon-sense to replace
Cost-effective measures means the staple
gas heating with heat pumps, so heat pumps
measures that tend to be installed under CERT,
are in fact not installed for that particular
with a payback typically between two and
scenario. The assumption is then that 50 per
seven years. The latter is generally the
cent of homes receive biomass boilers and 50
maximum time horizon seen by owner-
per cent just have high-efficiency gas heating
occupiers to recover their costs.
systems, with 50 per cent of flats converted to biomass CHP.
31
Energy Saving Trust, 21 Dartmouth Street, London SW1H 9BP, Tel 0845 602 1425, www.energysavingtrust.org.uk C0156 © Energy Saving Trust September 2008. E&OE.
Executive summary The United Kingdom has a goal of reducing its
that there is only a small number of ways to
overall carbon dioxide (CO2) emissions by 60 per
reach a 60 per cent - 80 per cent reduction in
cent by 2050, and this figure may well increase
emissions. This report shows that we can
to 80 per cent. It is likely that we will need to
achieve, with today’s technologies, and without
achieve this level of reduction from our housing
any improvements in appliance use, the
stock. This is because there is a high potential
following:
for sustainable energy measures in housing, many of which are cost-effective even today. The necessary measures will not actually be installed as a matter of course. They need a variety of support, including regulation, promotion, and supply chain development. Some of this may entail politically difficult
16 per cent reductions from installing all energy efficiency measures at current grid carbon intensity. 25 per cent reductions from simply installing currently cost-effective measures and median decarbonisation of the grid.
decisions, active changes in behaviour and
50 per cent reductions if we “throw
attitude, and upfront, long-term industry
everything” at the housing stock, both
investment. In order to justify and give context
insulation and microgeneration, and implement
to such changes, there is a need for a strategy
a programme of behaviour change, at current
for the improvement of the housing stock to
grid intensity.
2050.
68 per cent reductions from “throwing
Such a strategy needs to identify the total
everything” at the housing stock together with
potential for measures to reduce emissions.
a programme of behaviour change, and
And it needs to identify the least-cost route to
achieving a median decarbonisation of the grid
securing these. It is important to understand
(see figure).
Figure: “Throwing everything at the housing stock,” together with programme of behaviour change, and median decarbonisation of the grid
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
Year
4
2037
2042
2047
The benefits of using trigger points 1. The householder is already thinking of undertaking works, so is receptive to ideas. 2. Workmen may already be on site, so there is little additional disruption and hassle. 3. There is scope to incorporate improvements, that will be lost once the works are complete. 4. The cost of improvement work may be less as workmen, scaffolding, etc. are already on site. 5. There is the potential to regulate and enforce, rather than relying purely on marketing.
Notable trigger points with potential include: moving home
change of tenancy
reroofing
new windows
extension
loft conversion
scaffolding
new kitchen
new bathroom
reflooring
Even more can be achieved towards or beyond an 80 per cent reduction with initiatives to reduce appliance usage, although these have not been investigated here. Likewise, new technologies with better performances are likely to become available between now and 2050 but are also outside the scope of this
new heating system
Recommendations The report sets out what is technically possible, and the contribution of various policies towards achieving this. In this context, the Energy Saving Trust would like to see: •
A long-term target of 80 per cent by 2050, together with interim targets, for emission
report.
reductions from the housing stock
The report also shows that we can accelerate the uptake of a variety of measures, and
large-scale refurbishment
•
A programme of public engagement to
achieve additional savings, by taking advantage
help gain buy-in into the technologies and
of the naturally occurring opportunities for
policies required to effect the emissions
improvement – “trigger points” – over the
reductions required.
course of the lifetime of each and every home.
•
Building Regulations (2010) to extend
Improvements can often be effected at these
coverage of triggers for improving the
points far more easily than at other times.
energy performance of existing homes,
The significance and importance of such trigger
including extensions, loft conversions, etc.
points can only be fully understood, and
•
A signal that the recommendations of
therefore action justified in relation to them, if
Energy Performance Certificates will
they are seen in the context of a long-term
become mandatory by a certain date in the
strategy. It is hoped that this report from the
future, say 2015, for home sales, rental,
Energy Saving Trust provides such context.
etc. •
A variety of incentives and awareness raising activities, developed around people’s behaviour and the lifetime of their homes, in preparation for eventual mandation.
5
These recommendations can be taken forward
•
now. As set out earlier, there is only a small number of ways to reach a radical reduction in emissions from the housing stock, and the
and lighting usage. •
impact of keeping temperatures at today’s
these. There are, of course, uncertainties: the
levels).
future cost of technologies; the emergence of •
Introduction of energy price projections and associated fuel bill savings and paybacks.
name but a few. We cannot however wait until these uncertainties are resolved. This is not only
Impact of behavioural campaign for optimum usage of home (beyond modelled
recommendations are consistent with all of
new technologies; and grid carbon content to
Impact of measures to reduce appliance
•
because we have national and international
Impact of policies on the EPC rating profile (A-G) of the housing stock.
obligations to meet interim carbon reduction targets; but because unless we press ahead, encouraging behavioural change and investment in new technologies, we will both miss existing opportunities and fail to open up
2. Further work expanding on the model: •
implemented as part of wider works.
new ones. A long-term strategy, the development of immediate policies and the
•
•
Impact of various levels of incentive and encouragement before mandation, building
Further work
on the Energy Saving Trust consumer
There are a number of further areas that could Saving Trust’s work to date including:
Capital cost reductions with time and with volume installations.
provision of policy signals, are needed now.
usefully be looked into, building on the Energy
Marginal capital cost when measures are
segmentation model. •
New technologies and improved technology performance.
The Energy Saving Trust will consider which of 1. Further exploration of the model: •
Impact of proliferation of domestic air conditioning, and measures to counter this.
6
these to take forward, depending on interest and resource availability.
Introduction In 2006 the Energy Saving Trust made a
The report is based on a model of CO2
submission to Government as part of the Review
emissions from the housing stock, produced for
of the Sustainability of Existing Buildings. The
the Energy Saving Trust by Element Energy Ltd.
submission recommended the development of a
The model focuses on improving the fabric and
long-term strategy for reducing CO2 emissions
services of the home, although it does allow
from the housing stock by 2050. The reduction
for some behavioural change and for variations
proposed was 60 per cent, the Government’s
in appliance energy use.
long-term goal for overall CO2 emissions
The report sets out the Energy Saving Trust’s
reductions, although the Energy Saving Trust
conclusions drawn from the model. However, it
supports moves to revise this to 80 per cent.
is hoped that Government and other
This report sets out in more detail the
stakeholders will engage in debate and will
importance of having such a strategy. In
make use of this and other models, to develop
particular, it focuses on the opportunities for
a strategy and much needed policies for the
improving the energy performance of homes -
long-term improvement of the housing stock.
opportunities that occur naturally over the lifetime of these homes but that are in the main currently being missed. The report looks
CO2 emissions targets
at how these opportunities could be grasped,
The United Kingdom has a goal of reducing its
and the impact on long-term CO2 emissions
overall CO2 emissions by 60 per cent by 2050.
from the housing stock.
The Climate Change Bill 2008 anticipates the
The report has been produced in the context of
setting of a reduction target of 26-32 per cent on
a number of seminal publications in this area,
1990 emission levels by 2020, and 60 per cent by
notably: “Reducing Carbon Emissions from the
2050, with the possibility of this being raised to
UK Housing Stock” (BRE), “Stock Take” (SDC),
80 per cent in view of emerging climate change
“40 per cent House,” “Home Truths” (both by
science. These targets will be enshrined in
ECI), and most recently, “How Low” (WWF).
legislation.
What the Energy Saving Trust wishes to add to
It is likely that we will need to achieve these levels
the agenda is the consideration of using
of reduction from our housing stock. This is
naturally occurring opportunities as “trigger
because there is a high potential for sustainable
points” for implementing the housing
energy measures in housing, many of which are
improvements discussed in all of these
cost-effective even today. Indeed, other sectors
publications.
may be more difficult or costly to tackle.
1
However, emissions from the housing stock are reducing very slowly, as shown in figure 1:
1 Full references: “Reducing Carbon Emissions from the UK Housing Stock,” BRE for DEFRA, 2005; “Stock Take: Delivering Improvements in Existing Housing”, Sustainable Development Commission, 2006; “40% House,” Environmental Change Institute, February 2005; and “Home Truths - A Low-Carbon Strategy to Reduce UK Housing Emissions by 80% by 2050,” Environmental Change Institute, November 2007; “How Low – Achieving Optimal Carbon Savings from the UK’s Existing Housing Stock,” WWF-UK, 2008.
7
Figure 1: CO2 emissions from the UK housing stock 60
Million tonnes of carbon
50 Oil
40
Electric Gas
30
Solid
20 10 0 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Year
BRE March 2008
Note vertical axis is MtC, not MtC02 as used in later graphs
In fact, assuming current trends in energy
Even assuming: a) ongoing uptake of cost-
efficiency improvements and grid carbon intensity
effective energy efficiency measures under the
(relatively static), we would have a significant
Carbon Emissions Reduction Target (CERT),2 and
increase in CO2 emissions by 2050. This upward
b) the achievement of the 2016 zero-carbon
trend is the result of increasing internal
target for newbuild housing not only in England
temperatures, increasing appliance usage, and
but across the UK, our emissions by 2050 would
increasing number of homes.
be more or less back up to their current levels:
Figure 2: Long-term emissions at current grid intensity, ongoing uptake of energy efficiency at CERT levels, and achievement of 2016 zero-carbon newbuild target
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions. 2 CERT targets account for the majority of cost-effective energy efficiency installations in existing housing. It is assumed here that the suppliers obligation will continue at a similar level to CERT.
8
It is possible that the grid will decarbonise
does not achieve the reductions we need;
significantly by 2050, say to 50 per cent of
third, grid decarbonisation is not guaranteed to
today’s carbon content. Together with the
happen, and fourth, simply presenting
assumptions above on accelerated uptake of
“upstream” solutions does not lead to
energy efficiency and achievement of the 2016
behavioural and culture change on wider
newbuild target, this would reduce our CO2
sustainability, and at best will turn out to be an
emissions by some 20 per cent as shown in
interim fix.
figure 3.
For all these reasons, the Energy Saving Trust
However, we cannot rely solely on such grid
believes a coherent range of housing related
decarbonisation; first, if we use clean energy
policies is needed if we are to ensure successful
inefficiently, we will need a lot more of it;
achievement of our 2050 target.
second, moderate grid decarbonisation alone
Figure 3: Long-term emissions at reduced grid intensity, ongoing uptake of energy efficiency at CERT levels, and achievement of 2016 zero-carbon newbuild target
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
9
The need for a clear strategy
The longer we leave it, the steeper the reductions curve. This is not only because we
It has been shown that much more is needed to move us away from the “business-as-usual” trajectory of CO2 emissions. Action is
will have less time to reach the same target, but also in physical terms (even if not in terms of conventional thinking on targets) because
needed both on newbuild and on existing housing. It needs to be recognised that the less we do on one, the more we must do on the
we must compensate for the additional emissions that have accumulated in the atmosphere in the intervening period. So a
other.
linear 60 per cent goal set in 2000 actually
The action necessary may include upfront
corresponds to a roughly 75 per cent linear
investment or politically difficult decisions such
goal if started in 2010, and the same goes for
as stronger regulatory requirements. In order to
the impact of delaying the introduction of
justify difficult decisions, effect culture change,
action towards a possible 80 per cent reduction
and secure long-term industry investment, we
target.
need to have a long-term strategy.
Figure 4: Indicative emissions profile from new and existing housing to achieve 80% reduction
45 Total CO2 emissions on 2005 baseline
40 35 30 25 20 15 10 new
5 0 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
existing
Year
*Note vertical axis is MtC, not MtCO2 as used in later graphs.
10
Figure 5: CO2 emissions trajectories for equivalent amounts of accumulated atmospheric carbon
Percentage of 2000 CO2 emissions
120 100 60 60 40 20 0 2000
2010
2020
2030
2040
2050
Year
The model The model used for this report is based on EHCS data, aggregated up to UK household numbers. It can be adapted to accommodate the specific needs of the Devolved Administrations. We believe what is new about the model as a tool is that it is sufficiently versatile to simulate a range of policies, and packages of sustainable energy measures, to improve the housing stock over the course of time from the present to 2050. It allows the setting of policies that trigger various improvements at certain points over the lifetime of the property. The model assumes a baseline trend consistent with anticipated activity under the Carbon Emissions Reduction Target (CERT) followed by the supplier obligation at a similar level, and the impact of further policies is assessed against this. The model focuses on the house itself. Domestic air conditioning can be modelled, though it has not been investigated in this report. Appliance emissions are included, but are not disaggregated by type of appliance. This can be done as follow-on work if needed. Further
developmental work would be needed to model the impact of new, as yet unspecified technologies, and of a behavioural campaign for optimum usage of the home (beyond the modelled impact of keeping temperatures at today’s levels). Further detail on the model is provided in Appendix A.
The potential for improvements to the housing stock We can reduce CO2 emissions associated with buildings (i.e. space heating, water heating, and lighting) by over 60 per cent and more in many homes today, using existing technologies and without resorting to full-on microgeneration. This can be done through a combination of:3 •
installing all the cost-effective insulation measures
•
internally or externally cladding non-cavity walls
•
upgrading the heating system
•
adding solar thermal water heating.
3 See:“Refurbishing Dwellings – A Summary of Best Practice,” Energy Saving Trust, 2007, for an illustration of savings and how these can be made.
11
This is shown for a common, Victorian terraced property: Figure 6: The contribution of individual measures to a 60% reduction in emissions kg/CO2/m2/yr 70 60
59.1
58.1
55.8
50 40.4
40
34.1
31.9
30
22.2
20
19.8
10 0
Base
100% low energy lights
Floor (0.17)
Walls (0.30)
Windows (1.5) and draughtproof
Roof (0.16)
Solar Heating thermal (91% condensing (4m2) with controls
Energy Saving Trust Best Practice programme
The relative contribution of wall insulation
Because many solid walled homes are long,
should not be underestimated. Objections to
or deep, the front wall can be internally
the insulation of non-cavity walls on the basis
insulated without significant relative loss of
of aesthetics need to be addressed, but are not
floor area.
necessarily insurmountable: •
•
Additional microgeneration measures, for
The back and sides of solid-walled homes
example, biomass boilers, heat pumps, can
can generally be insulated externally with
then reduce the emissions from the home
little negative effect on overall aesthetics.
still further.
The front façade forms a relatively low proportion of surface area on many solidwalled homes.
12
•
The impact of applying the full range of energy
These technical improvements can be
efficiency and a wide range of microgeneration
enhanced by a national campaign to keep
measures universally, compared with an
average internal temperatures at their current
otherwise upwards trend in CO2 emissions, is
level of 18oC, delivering still more carbon
shown in figure 7 to result in over 40 per cent
reductions, almost 50 per cent, as shown in
carbon emission reductions.
figure 8.
Figure 7: Comprehensive energy efficiency and microgeneration measures applied to all homes4
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027 2032 Year
2037
2042
2047
See Appendix for full set of assumptions.
Figure 8: Comprehensive energy efficiency and microgeneration measures applied to all homes together with behavioural campaign5
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2042
2047
Year See Appendix for full set of assumptions.
4 Under this scenario, all homes are internally or externally insulated and 50% of homes have biomass boilers. There is little benefit in converting gas heated homes to heat pumps at current grid intensity. 50% of flats are converted to biomass CHP. 5 Assumes that internal temperatures remain constant at 2007 levels.
13
This highlights the importance and value of
hot water usage, turning off lights and
engaging people and encouraging changes
appliances.
in attitude and behaviour, not just focusing solely on technical solutions. In fact, there are still more savings likely to be had through optimum use of the home beyond
Pure energy efficiency measures, i.e. the above scenario without microgeneration, would deliver some 16 per cent reductions:
keeping temperatures constant – for
Utilising only the cost-effective energy efficiency
example, switching heating off when not
measures would fall well short of our target,
needed, better zoning of heating, prudent
and not deliver the step change that is needed:
Figure 9: Comprehensive energy efficiency measures applied to all homes
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
14
Figure 10: Comprehensive cost-effective energy efficiency measures only, applied to all homes
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This highlights the need for focused activity to
grid, relying solely on the above cost-effective
bring further, currently more expensive
measures and not investing in further housing
measures on stream, and to create market
improvement measures would fall well short of
demand for these.
our target, achieving only a 25 per cent
Even with halving of the carbon intensity of the
reduction in CO2 emissions as shown below.
Figure 11: Comprehensive cost-effective energy efficiency measures applied to all homes, together with grid decarbonisation
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2032
2047
Year See Appendix for full set of assumptions.
15
Figure 12: Comprehensive energy efficiency and microgeneration measures applied to all homes, together with behavioural campaign and grid decarbonisation6
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2012
2017
2022
2027
2032
2037
2032
2047
Year See Appendix for full set of assumptions.
However, as shown in figure 12, if we applied
driven - in terms of public opinion, local
all household measures, and behavioural
opposition, and Ministerial inclination. As such,
measures, together with grid decarbonisation,
reliance solely on future decisions for a low-
then we are verging on a 70 per cent reduction
carbon grid is risky. Furthermore, in the event
in CO2 emissions:
that we are off target or need to achieve more,
What these figures show is that there is only a small number of ways to reach a 60 per cent-80
it is difficult to fine-tune grid intensity, given the timescales for making investment decisions.
per cent reduction in emissions from the
External cladding can also be a controversial
housing stock. And that for those that do
measure, for two reasons:
achieve this, energy efficiency, microgeneration, consumer attitudes and grid decarbonisation all
•
looking properties.
need to be aligned, in roughly equal measure. There is no point in waiting to see which is
It is generally opposed on traditional
•
It may not fit in with the local vernacular, even if this is not “traditional.”
“better.” All are needed.
Therefore there would need to be public Risks and sensitivities Decisions on investments in power generation
engagement and an area-based approach if this measure was to form a significant part of the strategy.
can be highly controversial and politically
6 This scenario entails 50% of homes with biomass boilers and 50% with heat pumps. – Once the grid carbon intensity begins to drop, it begins to make carbon-sense to replace gas heating with heat pumps.
16
In economic theory, it makes sense to wait for
order for householders to be receptive to CERT
the cost of technologies to come down and for
offers; b) many householders simply do not
other uncertainties likewise to be resolved.
trust their energy supplier to offer them energy
However, in practice, industry capacity issues
saving measures; c) CERT does not have an
are of crucial importance. The earlier industry
absolute carbon cap and it is uncertain how
can be geared up, the less of a step-change is
the provision for influencing consumer
required and the more realistic it is to achieve
behaviour will be used; and d) CERT does not
the target.
take a strategic, market transformation
Politically also, we are obliged both to meet
approach to particular technologies.7
international targets, and to show leadership
In short, energy supplier activity is a very
on the world stage by delivering emissions
important part of a housing improvement
reductions now, not just promising them for
strategy – but it is not a housing improvement
the future. Having said that, we need to meet
strategy itself, and this is what is needed.
our interim targets without jeopardising our long-term strategy.
The most effective point at which to ensure the necessary measures are installed is often when the householder is already thinking of
The policies for improvements Clearly, CERT will achieve a significant improvement in the uptake of cost-effective measures. However, even if we increase the CERT target under the Supplier’s Obligation, some housing simply will not be addressed.
undertaking works, or is indeed doing so. There is an argument that requiring additional sustainable energy measures at the time of works will simply discourage people from having such works done in the first place. This issue needs to be addressed with appropriate incentives and enforcement. There are parallels
We cannot solely rely on CERT because, despite
with minimum standards, and indeed health
its undoubted effectiveness, it has a number of
and safety regulations in any field, which is not
limitations. These have been shown to be as
a reason not to introduce these.
follows: a) there is a need for awareness raising and the provision of impartial information in
The benefits of using trigger points 1. The householder is already thinking of undertaking works, so is receptive to ideas. 2. Workmen may already be on site, so there is little additional disruption and hassle. 3. There is scope to incorporate improvements, that will be lost once the works are complete. 4. The cost of improvement work may be less as workmen, scaffolding, etc. are already on site. 5. There is the potential to regulate and enforce, rather than relying purely on marketing.
7 See Energy Efficiency Innovation Review, Defra, 2005.
17
The policies modelled in this report feed off a
We also need to consider what happens over
number of “trigger points” over the lifetime of
the lifetime of a home in each sector as shown
the housing stock. This means looking at the
in figure 14.
breakdown of our housing stock as shown in figure 13.
Figure 13: Indicative breakdown of housing stock to 2050 Projection of UK housing stock: by tenure 40 35
Houses (millions)
30
Post 2007: Social
25
Post 207: Private rented
20
Post 2007: Owner occupied
15
Pre 2007: Social 10
Pre 2007: Private rented
5 0 2006 2010 2014 2018 2022 2026 2030 2034 2038 2042 2046 2050
Pre 2007: Owner occupied
Year
Figure 14: Opportunities for effecting improvements over the lifetime of a home
100%
Boiler replacement Home moving
Reroofing Extension built
tC/yr
Window replacement Change in energy supplier
New heating system Conversion to flats 20%
2005
18
Year
2050
We then need to take advantage of each of
It is important furthermore to view the
these trigger points by establishing a
trajectories in the context of an ongoing
mechanism for ensuring that they lead to
programme of energy supplier targets, i.e.
improvements in energy performance.
CERT, followed by the Supplier Obligation. The
A number of scenarios are modelled in the following. These scenarios describe the carbon impact of utilising various trigger points. They do not describe the policy mechanism itself, which may be a combination of regulation, awareness raising, supply chain capacity, and grant support. This is consistent with the aim of this report, which is to set out what needs
emissions reductions associated with the scenarios proposed could be considered as additional to energy supplier activity; or they could be considered as simply absorbed within the setting of higher energy supplier targets in years to come. Either way, it is clear that without the policies set out below, obvious opportunities to save carbon will be lost.
to happen, thereby giving a clear framework
This scenario entails a requirement that all the
for Government to introduce the appropriate
currently cost-effective recommendations of
mix of policies.
Energy Performance Certificates be
The carbon emission trajectories are set out individually for each scenario. They cannot
implemented upon the sale of a home, from some point in the future, say 2010.
simply be added, because there are inter-
The scenario brings forward the installation of
relationships. For example, if it is mandatory to
cost-effective measures, ensuring that we meet
install all EPC recommendations when
interim targets and pave the way for further
refurbishing a home, then there are no further
measures in the future. An additional 5MtCO2
savings to be had when selling that home, even
(3.5 per cent) would be saved over the course
if implementation of EPC recommendations is
of the decade.
again mandatory at that point.
Figure 15: All cost-effective recommendations of EPC mandatory upon home sale
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year
19
Figure 16: All cost-effective recommendations of EPC mandatory upon home sale, including advanced measures from 2020.
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
Whilst mandation may be politically
internal or external wall insulation and of
contentious in the short term, plenty of
advanced glazing will have reduced somewhat,
advance warning, together with a mix of
and that there will be public acceptance of the
incentives to improve the home in the
requirement to install more expensive measures
intervening period, would seem to be a fair
in the interests of climate change mitigation.
way of presenting such a policy to the British
These measures will therefore also be
public.
mandated upon home sale by 2020.
As shown above, this scenario builds on the
The scenario begins to make inroads into long-
policy of mandatory implementation of cost-
term carbon emission reductions, saving some
effective EPC recommendations upon home
20MtCO2 (15 per cent) by 2050.
sale. It assumes that, by 2020, the cost of
20
Figure 17: All cost-effective recommendations of EPC mandatory upon building of extension. 145
CO2 emissions (millions tonnes)
140 135 130 125 120 115 110 105 100 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails a requirement that all the
The rationale for this policy is that, if a
currently cost-effective recommendations of an
householder is increasing their carbon footprint
Energy Performance Certificate are
by building an extension, it seems only
implemented for the whole home, when an
fair that they install the cost-
extension is built.
effective measures, in the
Whilst the contribution is small in immediate carbon terms, “consequential improvements” are a useful mechanism for triggering necessary and fair improvements, and can be
rest of their home in order to compensate at least to some degree.
built on with time. Note that in an
It should also
environment where housebuilding and house
be noted that
sales are declining, it is likely that the number
the changes
of extensions, and therefore the carbon
will benefit the
footprint associated with extensions, will
householder.
increase.
This scenario
21
Figure 18: All cost-effective recommendations of EPC mandatory upon building of extension, including advanced measures from 2020. 145
CO2 emissions (millions tonnes)
140 135 130 125 120 115 110 105 100 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
builds on the policy of mandatory implementation of cost-effective EPC recommendations upon the building of an extension. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of measures such as internal or external wall insulation, and advanced glazing, when householders wish to increase their carbon footprint by building an extension. The impact of “consequential improvements” with the inclusion of these measures amounts to almost 3MtCO2 (two per cent) savings by 2050.
22
Figure 19 All cost-effective recommendations of EPC mandatory upon major refurbishment of a home (7 year refurbishment cycle assumed)
CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027 Year
2037
2047
See Appendix for full set of assumptions.
This scenario entails a requirement that all costeffective recommendations of an EPC be implemented upon major refurbishment of a home or estate or block of flats. Seven years is the average tenure of owner-occupied property, and is also an indicative maintenance schedule (including property management contracts) for many managed buildings. When a home is in any case being refurbished, implementing the EPC recommendations would seem an opportune time, leading to reasonable carbon savings. The resultant savings are particularly notable in the shortmedium term, i.e. some 12MtCO2 by 2016, and therefore useful for meeting interim
climate change targets. The savings by 2050 are 6MtCO2 (four per cent). Note that such a cycle of improvements could be mandated in the social sector relatively easily. This scenario builds on the policy of mandatory implementation of cost-effective EPC recommendations upon major refurbishment. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of internal or external wall insulation and of advanced glazing. The impact of this policy amounts to emissions reductions of 20MtCO2 (15 per cent).
Figure 20: All cost-effective recommendations of EPC mandatory upon major refurbishment of a home (7 year refurbishment cycle assumed), with advanced measures from 2020 CO2 emissions (millions tonnes)
160 140 120 100 80 60 40 20 0 2007
2017
2027 Year
2037
2047
See Appendix for full set of assumptions.
23
Figure 21: All cost-effective recommendations of EPC mandatory upon change of tenancy
CO2 emissions (millions tonnes)
17 16 15 14 13 12 11 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails a requirement to
The impact on the private rented sector of
implement all cost-effective recommendations
mandatory EPC implementation upon change
arising from the EPC before letting the
of tenancy is significant in the short-medium
property. Note that the production of an EPC is
term, at over 0.5MtCO2 (three per cent) for
mandatory for all new tenancies from October
that sector alone (only 12 per cent of the
2008.
stock) by 2016. This is helpful for reaching interim climate change targets, and also paves the way for mandating larger interventions further down the line. The policy of ensuring basic energy efficiency measures are installed in rented accommodation might furthermore be consistent with the need to raise living standards in this sector and protect low-income tenants from undue fuel poverty.
24
Figure 22: All cost-effective recommendations of EPC mandatory upon change of tenancy, including advanced measures from 2020 18
CO2 emissions (millions tonnes)
16 14 12 10 8 6 4 2 0 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario builds on the policy of mandatory implementation of of all cost-effective recommendations outlined in the EPC upon change of tenancy. Again, it assumes that it will be publicly acceptable by 2020 to mandate the installation of internal or external wall insulation and of advanced glazing upon change of tenancy. The savings from more advanced measures upon change of tenancy are substantial, at 4MtCO2 (25 per cent private rented sector emissions).
25
Figure 23: Mandatory solar panels (50% solar thermal, 50% PV) upon re-roofing.
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
26
This trigger point policy focuses on one
amount to 4MtCO2 (three per cent) by 2050.
particular part of the building, i.e: the roof,
Furthermore, the proliferation of solar panels
rather than the whole EPC. It requires that
through this mechanism would facilitate wider
either a photovoltaic array or a solar thermal
market transformation by fostering
system is installed upon re-roofing, and
acceptability and desirability of these
assumes a 50:50 uptake. Carbon savings
technologies.
Figure 24: All window replacements advanced glazing from 2016
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This trigger point policy focuses on another
The cost today would be high, but a signal that
part of the building, i.e. the window, in the
such a policy was forthcoming would secure
form of a minimum standard for replacement
ongoing industry investment and drive costs
products. It requires that every window
down, not to mention the development of new
replaced from 2016 onwards is triple glazed.
products.
The saving to 2050 is 2MtCO2 (1.5 per cent).
27
Figure 25: Replacement of coal/oil fuelled heating systems with biomass heating, together with gas condensing boilers replacing electric heating
CO2 emissions (millions tonnes)
150 140 130 120 110 100 90 80 2007
2017
2027
2037
2047
Year See Appendix for full set of assumptions.
This scenario entails the mandatory
this if grid carbon intensity remains at current
replacement of the worst polluting forms of
levels. Clearly, where there is no gas, other
heating with less carbon-intensive systems.
options for the replacement of electric systems
Coal/oil fuelled heating are replaced with
would need to be looked at.
biomass boilers, and electric heating is replaced with gas condensing boilers, upon the end of the life of the existing heating systems.
heating systems are substantial at 6MtCO2 (four per cent) by 2050. The necessary volume
Note that, in a median grid scenario, the
and supply chain for biomass fuel would also
electric heating might be replaced with a heat
need to be secured.
pump, but there is little carbon-sense in doing
28
The savings from replacing the worst polluting
Next steps Each of the above scenarios needs the detailed development of policy mechanisms to ensure that they are delivered. What is crucial to note
1. Further exploration of the model: •
conditioning, and measures to counter this.
is that the scenarios show ‘what’ needs to be achieved. We look forward to working with
•
Impact of measures to reduce appliance and lighting usage.
Government and other stakeholders on how this can be done, in the knowledge of the
Impact of proliferation of domestic air
•
Impact of behavioural campaign for
desired outcome.
optimum usage of home (beyond modelled
Key elements of activity the Energy Saving Trust
impact of keeping temperatures at today’s
would like to see are the development of:
levels).
•
A long-term target of 80 per cent by 2050,
•
associated fuel bill savings and paybacks.
together with interim targets, for emission reductions from the housing stock. •
Introduction of energy price projections and
•
Impact of policies on the EPC rating profile (A-G) of the housing stock.
A programme of public engagement to help gain buy-in into the technologies and policies required to effect the emission reductions required.
•
Building Regulations (2010) to extend
2. Further work expanding on the model: •
implemented as part of wider works.
coverage of triggers for improving the energy performance of existing homes,
•
including extensions, loft conversions, etc. •
A signal that the recommendations of
Capital cost reductions with time and with volume installations.
•
Impact of various levels of incentive and
Energy Performance Certificates will
encouragement before mandation, building
become mandatory by a certain date in the
on Energy Saving Trust consumer
future, say 2015, for home sales, rental,
segmentation model.
etc. •
Marginal capital cost when measures are
A variety of incentives and awareness raising activities, developed around people’s behaviour and the lifetime of their homes, in preparation for eventual mandation.
•
New technologies and improved technology performance.
The Energy Saving Trust will consider which of these to take forward, depending on interest and resource availability.
In addition, there are a number of further areas that could usefully be looked into, building on the Energy Saving Trust’s work to date. These are as follows:
29
Appendix A: Summary of the model The model used for this report is based on
A comprehensive range of microgeneration
EHCS data, aggregated up to UK household
technologies and building fabric measures is
numbers. It can be adapted to accommodate
included in the model. A housing stock model
the specific needs of the Devolved
is maintained for each year, from 2007 to
Administrations. Based upon an analysis of
2050, which includes data on technology
house condition survey data, the housing stock
lifetime and replacement rates. By applying
is reduced to 82 distinct housing types which,
these measures to appropriate houses, the
when added together, are representative of the
model is able to predict CO2 emissions from
stock as a whole.
each house type, and therefore from the
The factors delineating different house types
complete housing stock.
are: age of house (three age ranges); tenure
We believe what is new about the model as a
(owner-occupier, private-rented, social); heating
tool is that it is sufficiently versatile to simulate
fuel type (natural gas, electricity, oil,
a range of policies, and packages of
community heating, coal); size (small – flats,
sustainable energy measures, to improve the
medium – terraced houses, and large –
housing stock over the course of time from the
semi/fully detached); and condition (poor and
present to 2050. It allows the setting of
good). New house types are represented by 33
policies that trigger various improvements at
distinct house models.
certain points over the lifetime of the property.
Each of these house types has distinct settings
The model focuses on the house itself.
within an energy model, based on the
Domestic air conditioning can be modelled,
Standard Assessment Procedure (SAP) for
though it has not been investigated in this
thermal loads, and BREDEM for consumer
report. Appliance emissions are included, but
electrical loads. The model predicts energy
are not disaggregated by type of appliance.
consumption and CO2 emissions from each
This can be done as follow-on work if needed.
housing sector, and from the whole stock. UK
Further developmental work would be needed
domestic energy consumption predictions
to model the impact of new, as yet unspecified
from this model are calibrated against DUKES
technologies, and of a behavioural campaign
2007 data.
for optimum usage of the home (beyond the modelled impact of keeping temperatures at today’s levels).
30
Appendix B: Assumptions Baseline The baseline assumptions for all figures in this report are as follows: •
•
Comprehensive energy efficiency measures means all the currently available fabric and heating measures. This includes both the costeffective measures, and the more expensive
High grid carbon intensity at current levels,
measures such as internal or external wall
and constant until 2050.
insulation and advanced glazing (triple glazing
Achievement of zero-carbon newbuild
is modelled for this). It is of course recognised
policy from 2017 onwards across the UK.
that new and improved energy efficiency products will emerge with time, so a scenario
•
Internal household temperatures rise linearly from 18oC to 22oC by 2050.
cannot be truly comprehensive. Advanced energy efficiency measures mean
•
Ongoing CERT rates of uptake of basic energy efficiency measures until saturation.
•
those that are not currently staple, costeffective measures, i.e. internal/external wall
One per cent p.a. ongoing increase in
insulation and advanced glazing. It is
energy consumption of domestic
acknowledged that there are many more
appliances.
“advanced” or innovative measures.
The impact of all scenarios and policies is
Comprehensive microgeneration measures
assessed against this baseline.
means every roof having a PV or solar thermal system, and all heating replaced by either biomass or heat pumps. With a high-grid
Saturation scenarios
scenario, it makes little carbon-sense to replace
Cost-effective measures means the staple
gas heating with heat pumps, so heat pumps
measures that tend to be installed under CERT,
are in fact not installed for that particular
with a payback typically between two and
scenario. The assumption is then that 50 per
seven years. The latter is generally the
cent of homes receive biomass boilers and 50
maximum time horizon seen by owner-
per cent just have high-efficiency gas heating
occupiers to recover their costs.
systems, with 50 per cent of flats converted to biomass CHP.
31
Energy Saving Trust, 21 Dartmouth Street, London SW1H 9BP, Tel 0845 602 1425, www.energysavingtrust.org.uk C0156 © Energy Saving Trust September 2008. E&OE.
