Low Carbon Economy, 2010, 1, 61-70
doi:10.4236/lce.2010.12008 Published Online December 2010 (http://www.SciRP.org/journal/lce)
61
Adoption and Use of Household Microgeneration
Heat Technologies
Sally Caird1, Robin Roy2
1Des ign In novatio n Grou p, Ope n U niv e rsity, Milton Keynes, UK; 2De partmen t of Desi gn , Open Univers ity , Milton Keynes, UK.
Received October 7th, 2010; revised November 3rd, 2010; accepted November 30th, 2010.
ABSTRACT
The development and rapid household adoption of smallscale, low and zero carbon microgeneration technologies are
key elements of UK and EU strategies to meet the challenge of climate change. Microgeneration heat technologies, in-
cluding solar thermal hot water, heat pumps and biomass heating systems, have an especially important role in reduc-
ing the carbo n emissions from buildings. But d espite governmen t policies to promote microgene ration, adoption by UK
householders is very slow. Surveys by the Open University and Energy Saving Trust examined why over 900 UK
householders decided to adopt these technologies and why many do not. These surveys describe the niche market for
microgeneration heat as largely confined to environmentally concerned, older, middleclass householders, mainly living
in larger properties off the mains gas network. Although these pioneer adopters are generally highly satisfied, for mi-
crogeneration heat to expand beyond its market niche, several issues need to be addressed, includ ing: price reductions
and subsidies; independent information on the suitability, performance, payback and effective use of equipment; ‘one-
stop’ support from consideration to operation; improved system compatibility with smaller properties and existing
buildings an d hea ti ng systems; and more userfri endl y an d i nf or mat ive c o nt rol s.
Keywords: Microgeneration, Domestic Heating and Hot Water Systems, Renewable Energy, Consumer Surveys,
Usercentred Design and Marketing, Energy Policy
1. Introduction
1.1. The Importance of Low and Zero Carbon
Heat
Increasing the supply of renewable sources of energy is a
key element of the UK Government’s strategy to help
address key challenges of tackling climate change and
securing energy supplies [1]. In 2007 the European
Commission set the UK a target that 15% of energy
(electricity, heat and transport) should come from re-
newables by 2020, including smallscale, low and zero-
carbon microgeneration systems in domestic and other
buildings.
Tackling the heat demand is particularly important
because heating (both domestic and nondomestic) ac-
counts for the largest single proportion of the UK’s final
energy demand at approximately 49%. Households alone
contribute 27% of UK carbon emissions with approxi-
mately 75 per cent of these domestic emissions arising
from space and water heating [2,3].
A number of recent reports on the potential of local or
distributed energy stressed the importance of microgen-
eration heat technologies – the smallscale production of
heat from a low carbon source–to achieve the UK’s re-
newables and carbon emission reduction targets [4,5].
The government’s microgeneration strategy suggested
that widespread adoption of solar thermal hot water
(STHW) systems, heat pumps, biomass stoves and boil-
ers, and microCHP technologies, could reduce domestic
carbon emissions by up to 6.5% by 2030 and up to 15%
by 2050 [6]. Microgeneration heat could therefore play a
small but significant contribution to meeting the chal-
lenges of the 2008 Climate Change Act, in which the UK
government set demanding targets to reduce CO2 and
other greenhouse gas emissions by 34% by 2020 and by
80% by 2050 on 1990 levels [7].
But household adoption in the UK of microgeneration
technologies is slow compared to other EU countries
such as Germany, despite UK government support th-
rough grant schemes such as the Low Carbon Buildings
Programme. A recent detailed report by Element Energy

Adoption and Use of Household Microgeneration Heat Technologies 62
on the potential for microgeneration estimated that by
2007 that there were only 95,000 to 98,000 installations
in UK homes, including about 90,000 solar thermal hot
water (STHW) systems (over 92% of total installations),
less than 2,000 ground source heat pumps (GSHPs), and
500 to 600 biomass boilers [8]. Element Energy calcu-
lated that the UK market for domestic microgeneration
could reach 9 million installations by 2020 given an am-
bitious policy support framework, such as a subsidy of 2
p per kWh for microgenerated heat and prohibiting all
offsite (nonrenewable) electricity for zerocarbon homes,
except for low carbon systems such as heat pumps [8].
Under the UK Government’s Renewable Heat Incentive,
planned for introduction in 2011, more generous finan-
cial incentives for householders are proposed depending
on the technology concerned, ranging from 5.5 p per
kWh for small biogas systems and 7 p per kWh for
ground source heat pumps to 18 p per kWh for small
solar thermal systems [9]. If implemented, this policy
could lead to more widespread adoption of microgen-
eration heat technologies than forecast by Element En-
ergy.
Given the slow rate of takeup, UK reports tend to fo-
cus on the barriers to household adoption of microgen-
eration, especially those of high cost, lack of consumer
information and restrictive regulations such as planning
laws [5,8,10]. Some studies also include consumerrelated
barriers, such as the considerable technical knowledge
involved in purchase decisions [4], lack of trust in unfa-
miliar technologies and scepticism regarding the per-
formance of technologies like solar PV, microCHP and
microwind [1 1 ].
But additional reasons for the slow takeup of micro-
generation, especially beyond the enthusiast ‘early adop-
ters’, is that often equipment and systems have been de-
signed and installed without taking sufficient account of
user requirements and usability [12]. This paper moves
beyond the view of microgeneration systems as purely
functional, energy saving devices to consider user issues,
including equipment ergonomics and aesthetics, the sym-
bolic value of generating your own ener gy, and compati-
bility with existing buildings and heating systems. Un-
derstanding the ways people use microgeneration sys-
tems is also important because energy and carbon sav-
ings are not guaranteed by their adoption.
Consumers may reduce or cancel out carbon saving
benefits through ‘rebound effects’ such as increasing
room temperatures [13] or because they lack under-
standing of the equipment, find it difficult to make ad-
justments in their lifestyle, or simply do not use the
technologies as expected [14]. On the other hand adopt-
ing microgeneration may produce ‘double dividend’ be-
nefits, such as consumers improving their home’s energy
efficiency or their household energy saving behaviour.
1.2. Project Aims
To better understand how consumers perceive and ex-
perience low and zero carbon heating systems, the Open
University (OU) and Energy Saving Trust (EST) con-
ducted some of the largest surveys to date of UK house-
holders in the process of considering or purchasing mi-
crogeneration technologies for providing space heating
and/or hot water [10]. Two surveys, which together pro-
duced over 900 responses, revealed why UK consumers
purchase or decide against adopting these systems; and
provide insight into experiences of using low carbon heat.
The surveys covered four technologies, all eligible for
UK government grants under the householder stream of
the Low Carbon Buildings Programme (LCBP), which
ran from 2006 to 2010:
 Solar thermal hot water (STHW systems);
 Ground source heat pumps (GSHPs);
 Woodfuelled boilers (WFBs);
 Automatic pellet feed biomass room heaters or
stoves (BS systems).
The questions addressed in the project were:
1) Why do householders adopt, or decide against
adopting, microgeneration heat technologies for domestic
use?
2) What is the householder experience of purchase, in-
stallation and use of microgeneration heat systems?
3) What ideas for improvements to domestic micro-
generation heat systems would make them more desir-
able to consumers and effective in reducing carbon emis-
sions?
4) Do the ‘rebound’ and/or the ‘double dividend’ ef-
fect influence the carbon emission reductions achieved
with microgeneration heat systems?
5) What actions would encourage more householders
to install microgeneration heat technologies?
Findings for the surveys of the four selected micro-
generation heat technologies are presented below with
special attention to the most popular technologies; solar
thermal hot water systems and ground source heat
pumps.
2. Methodology
The two OU/EST surveys that were conducted provide a
purposive investigation of a sample of 924 ‘pioneer’
adopters and potential adopters of microgeneration heat
technologies, mainly living in England and Wales plus a
small number in Scotland and Northern Ireland. The first
survey was conducted with self-selected visitors to an

Adoption and Use of Household Microgeneration Heat Technologies 63
online questionnaire on the Energy Saving Trust and
Open University–British Broadcasting Corporation web-
sites. Two groups of consumers from the general public
responded, comprisin g: 314 householders who were con-
sidering purchase of one of these technologies (named
‘considerers’ of which 221 were considering a STWH
system; 50 a GSHP; 28 a WFB and 15 a BS); and 64
householders who had considered but decided against
any purchase (called ‘nonadopters’).
A second survey was conducted via email and weblink
with 546 UK householders who were randomly selected
from the LCBP database as a representative sample of
householders who had been awarded a government grant
to install a microgeneration system. This group was
named ‘adopters’, of whom 413 had chosen to install
STHW; 89 a GSHP; 36 a WFB and 8 a BS and who in-
cluded 285 households with a system already installed
and with experience of using microgeneration space
and/or water heating.
The major study by Element Energy, mentioned above,
which examined the growth potential for microgenera-
tion in the UK surveyed a representative sample of 1279
UK residents and established that only a minority (about
13%) had considered adopting microgeneration tech-
nologies [8]. The OU/EST surveys provide an indepth
study of the interest, motivations and experience of this
minority group. Only a fifth of the considerers in the
Element Energy study went on to obtain quotations from
installers with only 30% to 40% of these proceeding to
purchase, thereby suggesting that less than 1% British
residents actually adopt a microgeneration technology [8].
This finding is consistent with the number of domestic
systems installed which represent less than 1% of the 26
million UK households. The second OU/EST survey
offers a unique insight into a representative sample of
LCBP grant holders from the niche market of UK
households who have actually adopted a microgeneration
system.
The online questionnaires were designed to obtain
both multiple choices and open ended responses with
questions about the purchase, installation and experience
of using different microgeneration heat technologies,
plus questions about non adoption of seriously considered
but rejected technologies. The surveys also included
questions on household and property demographics.
We relied on users’ responses and estimates of house-
hold energy use rather than actually measuring carbon
and fuel bill savings following installation of a micro-
generation system. The survey results were analysed to
provide descriptive statistics and crosstabulations using
‘Questback’ survey solutions software (http://www.
questback.com/) and Excel software.
3. Results
3.1. Pioneer Households Considering, Adopting
or Rejecting Microgeneration Heat
Table 1 provides some of the household characteristics
of the survey samples, including considerers, adopters
and nonadopters. The table shows that the sample com-
prised households more than half of which included a
main earner that has (or is retired from) a professional or
senior managerial occupation and about a quarter of
which had an annual household income more than twice
the £30,000 (US$48,000) UK average. Over 60% of re-
spondents live in households without children or where
children have left home. In addition, not shown in the
table, up to half of respondents from all groups were en-
vironmentally conscious and said that they usually took
actions to reduce their energy and transport environ-
mental impacts, such as cycling, walking and using pub-
lic transport whenever possible instead of driving.
A striking characteristic of the adopters of microgen-
eration heat is that over half live in larger detached
homes with 4 or more bedrooms and large gardens (over
300 m2), located in rural areas, and off the UK’s mains
gas network. By comparison, though considerers and
nonadopters have similar occupational characteristics and
environmental attitudes, more live in suburban, semide-
tached or terraced homes with smaller gardens in areas
on the mains gas network. They were also more often
considering retrofitting rather than installing a system in
a newbuild property.
The main fuels displaced when microgeneration heat-
ing is installed are mains gas (42%), followed by oil
(29%) and electricity (8%). More specifically STHW
systems displace mains gas (54%) and oil (27%) while
GSHP systems mainly displace oil (33%) and electricity
(11%) with only 6% GSHP installations displacing mains
gas. Although there were too few biomass heating instal-
lations for statistical analysis, almost all were in rural
areas off the mai ns g as n et work.
This contrasted with only about half of STHW instal-
lations that were rural and offgas, confirming the wider
applicability of STHW systems.
More than a third of adopters were retrofitting micro-
generation heat systems in an older (pre 1919) property,
while a tenth installed the system when first moving into
a converted older property or into a newbuild (post 2006)
home. A higher percentage of GSHPs (about a third)
were installed in new buildings.
Unsurprisingly, GSHPs were typically installed in
properties with larger gardens than other systems; three
quarters were installed in gardens/land of over 300 m2,
and 57% were installed in large plots of at least 1,000 m2.

Adoption and Use of Household Microgeneration Heat Technologies 64
Table 1. Household and property characterist ics: considerers, ad op ters an d nonadopters of microgeneration heat technologies.
Household and property Characteris tics Total considerersTotal nonadopters Total adopters
Professional or senior manager ial occupations (1) 59% 78% 69%
Total annual household income (of all ear ners, before tax) > £60,000 (2) 24% 20% 28%
Households with no children (< 18 years normally resident) 57% 63% 64%
Live in detached house/bungalow 47% 44% 73%
4+ bedrooms house 42% 40% 62%
House built before 1919 29% 20% 38%
Live in newbuild house built post 2006 3% 0% 10%
With medium/large garden or l and (over 300 m2) 39% 44% 65%
Properties OFF mains gas network 12% 6% 54%
Live in rural location 46% 44% 65%
Live in urban/suburban ar ea s 54% 56% 34%
Number of responses 314 64 546
(1)4% adopters did not provide occupational information; (2)8% adopters did not provide their household income and 4% adopters responded ‘don’t know’.
3.2. Why Householders are Interested in
Microgeneration Heat
Table 2 shows that the main reasons why UK house-
holders are considering or decide to adopt microgenera-
tion heat technologies are that they wish to reduce their
household carbon emissions and fuel bills. But these
consumers also want to own a microgeneration system
for the anticipated pleasure of using a low or zero carbon
energy source and/or to demonstrate their environmental
commitment. A fifth of these microgeneration pioneers
have a job or hobby related to the environment or low
carbon technology and hence many are enthusiasts, mo-
tivated by an interest in the technologies themselves or
the desire to be a technology pioneer. A fifth of adopters
are also using the opportunity of a new build or other
major home improvement projects to install a microgen-
eration heat system.
3.3. Why Householders Decide against Adopting
Microgeneration Heat
Table 3 shows that financial barriers – high initial cost,
long or uncertain payback, and relatively small grants–
were the major deterrents for nonadopters. This led more
than half of nonadopters to respond that there are more
cost effective ways to reduce carbon emissions, such as
installing home insulation. Microgeneration heat has also
to overcome perceptual barriers such as lack of confi-
dence in the performance and reliability of unfamiliar
technologies, as well as practical barriers, especially lack
of suitable space and locations to install equipment, and
the frequent need to ad apt existing prop erties and heating
systems to be compatible with microgeneration.
Specific deterrents for 43 GSHP nonadopters included
concerns that in stallation of gr ound loops in trenches or a
borehole would involve great disruption to the garden
(51%) and the possibility of the system freezing or caus-
ing dryness to the soil (28%). A specific deterrent for
most of the 29 nonadopters of biomass heating systems
was the effort involved in sourcing fuel, refuelling and
ash removal.
3.4. The Purchase of Microgeneration Heat
Systems
Our survey results show that when choosing between
microgeneration heat technologies householders gener-
ally adopt the one perceived to be less risky (40%); more
compatible with their property (37%), with better estab-
lished information (26%); lower priced and with faster
payback (25% ) .
When householders consider buying microgeneration
heat technologies they usually seek impartial information
on the internet, in manufacturers’ or other literature, as
well as advice from family, friends and installers. Poten-
tial purchasers often review more than one technology
before making their choice. On average the 546 house-
holds who proceeded to purchase a microgeneration heat
system organised two to three installer visits and typically

Adoption and Use of Household Microgeneration Heat Technologies 65
Table 2. What drives people to seriously consider or adopt microgeneration heat technologies?
Reasons given Percent
To reduce carbon dioxide emissions 75%
To save money on fuel bills 72%
I wanted to use low carbon energy and will get pleasure from doing so 61%
Allows me to visibly demonstrate my environmental commitment 34%
The low carbon technology forms part of a heating system replacement or upgrade 23%
Related to my job, hobby or interests in the environment/low carbon technologies 21%
Being innovative, a pioneer in u sing low carbon energy technology 21%
The low carbon technology forms part of other home improvements e.g. home extension; loft
conversion, new build 20%
Had funds available to help purchase the system 20%
Had confidence in the performa nc e and reliabil ity of this technology 19%
Total responses: Considerers and Adopters n = 859
Table 3. Barriers to adoption of microgeneration heat technologies.
Nonadopters saying this issue was ‘very’ or ‘fairly important’ in deterring adoption Total nonadopters(1)
Purchase price 86%
Pay back on the investment is uncertain or long 68%
Grant(s) only 10% to 20% of the purchase price 60%
Performance and reliability u n c e r tainti e s 58%
More cost effective ways to red uce carbon emissions 56%
Possible major modifications to my existing heating, hot water or electrical systems 54%
Difficulties finding space or suitabl e location 50%
Time and effort involved in investigating and installing 47%
Total responses: Nonadopters 132
(1)Our surveys with 132 nonadopters included a special group of 70 LCBP grantholders who had rejected a microgeneration heat
technology in favour of another LCBP microgeneration heat or electricity generating technology.
choose installers who appear to be knowledgeable, trust-
worthy and reliable (49%), local (32%), and (preferably)
with a personal recommendation (21%). Since installers
tend to specialise in specific technologies they typically
cannot offer specialised advice to householders trying to
choose between alternative microgeneration and other
heat technologies. This places the onus on adopters to
understand their choices, leading to over a quarter (28%)
mentioning the time and effort involved in investigating
microgeneration technologies.
3.5. Users’ Experience of Using Microgeneration
Heat
Only 285 households had actually installed and were
using microgeneration heat, including 217 STHW systems
and 48 GSHP systems. Table 4 shows that householders
who adopt microgeneration heat systems are generally
very satisfied with their performance and reliability and

Adoption and Use of Household Microgeneration Heat Technologies 66
Table 4. Adopters’ satisfaction using microgeneration heat system.
Satisfaction indicator(1) Total adopters with
experience of use(2) STHW adopters GSHP adopters
System meets household demands for heating and/or hot water 74% agree
3% disagree 71% agree 3% disagree 83% agree 2% disagree
System performs reliably 86% agree
3% disagree 88% agree 2% disagree 85% agree 0% disagree
Get pleasure from using low carbon energy 92% agree
0% disagree 93% agree 0% disagree 87% agree 0% disagree
Satisfactory appearance 87% agree
3% disagree 86% agree 1% disagree 94% agree 4% disagree
Satisfactory instructions on operat ing and using system 64% agree
6% disagree 65% agree 6% disagree 52% agree 8% disagree
Controls provide feedback on efficient system use 44% agree
20% disagree 47% agree 19% disagree 30% agree 30% disagree
Satisfactory costs of running and m a intaining t he system 70% agree
2% disagree 72% agree 0% disagree 58% agree 6% disagree
Reductions in fuel bills are as expected 46% agree
4% disagree 47% agree 3% disagree 40% agree 6% disagree
Total responses 285 217 48
(1)‘agree’ and ‘dis agree’ resp onses incl ude stron gly agree/s trongly d isagree. (2)responses from 15 woodfuelled boiler adopters and 5 biomass stove adopters are
included in the total.
92% say they get considerable pleasure from using low
carbon heat. However, less than half of all users (46%)
said that the reductions in their fu el bills were as great as
expected (although this was before major fuel price rises
in the UK).
Not s hown in the table is the res ult that many of the se
adopters (59%) required unexpected modifications to
their existing heating and hot water system during in stal-
lation. This particularly affected twothirds (67%) of
STHW adopters, while twothirds (69%) of GSHP adopt-
ers complained about the disruption to their property or
garden during i nstal l a t i on.
A small percentage (12%) of all users complained th at
their system provided less than expected of their house-
hold’s heating and/or hot water requirements. A few
GSHP adopters (10%) also complained about the slow
warmup of their heating and/or inability to heat rooms to
the required temperature. GSHPs produce lower flow
temperatures than a boiler and so response times can be
slow.
A specific complaint, made by a third (32%) of STHW
users, is disappointment at not being able to use solar-
heated water in their coldfill washing machine and/or
dishwasher. This problem may be attributed to plumbing
constraints or modern coldfill only appliances. It appears
that the adapter valves available in Germany and else-
where to allow use of solar heated water in coldfill ap-
pliances are not supplied by UK installers.
The most common problems experienced by over a
third of all users was uncertainty about how best to oper-
ate the system to make most efficient use of fuel or en-
ergy (37%) and difficulties understanding the system’s
controls (28%). Table 4 shows that less than half of the
users are satisfied with the feedback they get from the
system’s controls on the energy and money they are sav-
ing, and a fifth are strongly dissatisfied. Poor usability
was a particular problem for GSHP users, with nearly
one third of them very dissatisfied with feedback pro-
vided by their system’s often sophisticated and comput-
erised controls.
3.6. Users’ Ideas for Improving Microgeneration
Heat
The main system improvements desired by microgenera-
tion heat adopters arose from the problems they experi-
enced in use. The improvements include more user-
friendly controls, better instructions on use of controls,
and improved feedback displays showing energy gener-
ated and carbon and money saved. This would help users
understand how to make the most efficient use of fuel
and maximise carbon and financial savings. Adopters
would also like improvements to the compatibility of
microgeneration techno logies with ex isting build ings and
heating systems.
Over half (57%) of 413 STHW adopters would like
systems improved to provide space heating as well as hot
water, probably not realising that such systems are
available but are not usually cost-effective in the UK

Adoption and Use of Household Microgeneration Heat Technologies 67
climate. Nearly half (48%) wanted easier to understand
STHW controls that minimise backup water heating use
and provide feedback on money and energy savings.
Over half 89 GSHP adopters (53%) would like con-
trols that give more feedback on operating efficiency (e.g.
electrical energy in and heat energy out) and energy
saved – rather like a car computer. Almost a quarter
would like higher heat pump efficiencies with existing
radiator and hot w ater systems (24%), and more compact
designs for ground collectors (22%) to allow GSHPs to
be installed in smaller house sites.
Nearly half (44%) of the woodfuelled boiler (WFB)
system adopters would like more compact designs
matched to smaller homes and 17% would like automatic
fuelling and ash removal. Most of the au tomatic biomass
stove (BS) adopters would like improvements to the in-
frastructure to provide a reliable supply of fuel pellets.
However, with samples of only 36 adopters of WFB and
8 BS systems, these desired improvements are only in-
dicative.
3.7. Carbon Reductions with Microgeneration
Heat
Although over threequarters of adopters say their system
meets their heating and hot water needs, as noted in Ta-
ble 4 only 46% were satisfied that their fuel bills have
reduced much as expected. This questions whether these
technologies are performing as well as designed.
When asked if the installation of a low carbon energy
system had led to changes in home energy use some us-
ers described ‘rebound’ effects. Thus a quarter of 272
users admitted that they were heating more of the home
and/or for longer periods, and 8% said they used more
hot water. But most users responded that they were not
heating rooms to higher temperatures or using more hot
water.
However, there was also some evidence of ‘double
dividends’ or additional carbon reductions that followed
installation of a microgeneration system, including in-
creased general household energy awareness and adop-
tion of additional home energy efficiency measures.
Three quarters of 272 microgeneration users said that
they are more aware of their energy use, make greater
efforts to save energy than before the installation, and
have adapted their patterns of use of space heating and/or
hot water to make most efficient use of the system.
The findings also show that although most of the 546
adopters had already installed energy efficiency meas-
ures before applying for a LCBP grant to help pay for the
system, the grant stimulated up to a quarter of adopters to
install extra insulation, new energy-saving lights and/or
heating controls. A fifth of all adopters went further and
installed additional energy saving measures over and
above the grant’s requirements, including underfloor
insulation (13%); hot water cylinder thermostats (19%);
A-rated domestic appliances (10%); and low-emissivity
double glazing (10%), while 2% also installed solar PV.
3.8. Encouraging UK Householders to Adopt
Microgeneration Heat
Reducing the initial cost of microgeneration heat systems,
thus addressing the biggest barrier to adoption, is proba-
bly the main way of widening appeal. Our survey found
price thresholds below which many more microgenera-
tion considerers and nonadopters said they would proba-
bly purchase a system. For example, £2500 to £3,000
was the maximum most microgeneration considerers were
prepared to pay for a retrofit STHW system, rather than
the £4000 average price in the UK. The maximum price
threshold for those considering a GSHP installation was
about £10,000, while many GSHP systems cost more
than that to install.
Other than directly reducing the price, the most popu-
lar financial support measure for microgeneration is local
council tax relief following system installation; favoured
by over half of all respondents (53%), while the least
popular measure was lowcost, long term loans for pur-
chase, favoured by on ly 18%.
Over two-thirds of all respondents would support new
building regulations that required householders in the UK,
as in some other countries, to install low carbon energy
technologies when undertaking major refurbishments,
extensions or conv ersions to their home.
Increasing consumer understanding and confidence in
microgeneration technologies is also needed to promote
wider adoption. Table 5 shows some of the information
and advice measures and support wanted by consumers
to help with the complex process of choosing and in-
stalling a system.
4. Conclusions
The UK microgeneration heat market is still at the early
phase of the adoption curve with significant barriers to
widespread market penetration [8]. The OU/EST surveys
show that microgeneration space and water heating sys-
tems currently mainly attracts ‘pioneers’ interested in
innovative green technolog ies and ab le to pay the upfro nt
installation costs, who are also driven by a desire to re-
duce their carbon emissions coupled with the hope to
save money and enjoy the pleasure of using low or zero
carbon energy. These findings reinforce our previous
research on the drivers for UK consumer adoption of
household renewables [15], as well as that of similar re-
search in Germany, Austria, Australia and the USA
[16-18]. Our surveys identify those considering or adopt-
ing microgeneration – estimated to be limited to about

Adoption and Use of Household Microgeneration Heat Technologies 68
13%
Table 5. Desired information and advice measures: all respondents.
Support measure Percent
Independent information on the performance and payback of dif ferent manufacturers’ systems 71%
Rank 1
‘Onestop shop’ assisting process of technology choice, grant application s, planning permission,
installation, use, mainte nance, and effective use 69% Rank 2
Online informati on to help ass e ss su i ta b il i ty of home for low carbon energy technologies 50%
Rank 3
More opportunity to see low carbon energy technologies installed in people’s homes and public
buildings 46% Rank 4
Multiskilled installers who suppl y different low carbon energy technologies and advise on the most
suitable 41% Rank 5
Total respondents n = 924
of British householders [8] – as currently largely con-
fined to a niche market of environmentally concerned,
middle class householders, and mainly those living in
larger rural properties off the UK’s mains gas network.
This description of the typical UK microgeneration
adopter applies especially to adopters of ground source
heat pumps, woodfuelled boilers and biomass stoves.
These technologies are more typically installed in larger,
rural, off gas pr op erties b ecause th ey are costly; curren tly
only cost- effective in properties previously heated by oil,
electricity o r solid fuel; wh ile GS HPs a n d WFB s are b ette r
suited to properties with sufficient space for the equip-
ment, ground heat collector s or wood fuel stores.
Solar thermal hot water accounts for over 90% of ex-
isting UK installations and was also the most frequently
adopted system in our surveys. Compared with other
microgeneration heat technologies, STHW has a wider
appeal because it is a lower cost, more compact and fa-
miliar technology, with a faster payback, worthwhile for
properties with or without mains gas, and suited both to
rural and urban/ sub ur ban dwellings.
For microgeneration heat to ex pand beyond the curren t
market niche, the views and concerns of the householders
seriously considering purchase of a microgeneration sys-
tem need first to be addressed followed by lowering the
barriers that are deterring adoption by the wider popula-
tion. These inc l ude:
 Cost reductions: Table 3 shows that pu rchase price
and payback issues are the barriers most cited by
nonadopters. Microgeneration has already benefit-
ted from UK purchase tax reductions (to 5%), and
prices could be brought down further by larger
grants, throug h lowercost production (e.g. from the
rapidly expanding Chinese microgeneration indus-
try) or by subsidies from energy suppliers as is re-
quired under the UK government’s Carbon Emis-
sions Reduction Target (CERT). A new renewable
heat incentive proposed by the UK government for
introduction in 2011 sh ould also help overco me the
payback barrier, but was not available at the time
of these surveys, when the most popular financial
support measure was local council tax relief for
households wi t h microgenerati on.
 Independent information: This would reduce the
requirement for consumers to rely on manufactur-
ers’ claims about the reliability and performance of
microgeneration technologies. Consumer confi-
dence would be in creased by greater availability of
independent information on the suitability, per-
formance, payback and carbon savings of different
manufacturers’ microgeneration systems. The need
for greater consumer confidence to invest in unfa-
miliar technologies may have been partly addressed
with the introduction in 2008 of a UK government
Microgeneration Certification Scheme [19].
 Better advice and support: Consumers would like
‘onestop’, independent, trustworthy advice and
support covering the whole process of technology
choice, grant applications, planning permission, in-
stallation, maintenance, and effective use. The
‘ActOnCO2’ advice service offered by the Energy
Saving Trust seeks to address difficulties UK con-
sumers have finding trustworthy, multiskilled in-
stallers.
 Less disruptive installations: More than half mi-
crogeneration heat users required unexpected mod-
ifications to their existing heating and hot water
systems. In some cases this led to additional cost
and pressures on microgeneration users to take a
strong installation coordination role.
 Design improvements to controls to make them
more userfriendly: with improved feedback dis-

Adoption and Use of Household Microgeneration Heat Technologies 69
plays showing the energy generated, carbon and
money saved. These improvements should help
overcome the difficulties some users experience in
understanding and operating their system effec-
tively.
There will always be some homes that are unsuitable
for microgeneration heat. For example STHW systems
suit properties with a mainly southoriented, unshaded
roof and a GSHP requires sufficient land to install the
ground collectors and space inside or outside the house to
accommodate the equipment. Likewise woodfuelled boi-
lers and biomass room heaters/stoves require suitable
locations for equipment and space for storing fuel. How-
ever, greater use of borehole GSHPs (which need less
space) and designing more efficient air source heat
pumps (which need no ground loop) would allow such
systems to be installed in more urban and suburban
homes. Similarly, more compact wood boilers and bio-
mass room heaters would encourage wider uptake.
The survey shows that householders who purchase
these technologies are generally very satisfied and derive
considerable satisfaction from using them (Table 4).
However, less than half of adopters were satisfied that
their fuel bill reductions were as great as expected , which
raises the question of whether the energy and carbon
savings predicted for microgeneration heat systems are
being achieved in practice. This may be partly due to the
fact that the way that people use microgeneration sys-
tems affects their performance. Also there may be ‘re-
bound effects’ if people use more heat or hot water as a
result of installing low or zero carbon energy technolo-
gies [13]. Although these surveys did not attempt to
measure carbon savings actually achieved (which is the
subject of the Energy Saving Trust’s field trial to monitor
the performance of domestic heat pumps1), the results
showed that adopting a microgeneration heat system of-
ten produces ‘double dividend’ benefits, such as house-
holders deciding to install additional home insulation
measures as well as encouraging greater energy saving
awareness and behaviour in the home. This supports
findings from other qualitative studies of the positive
impact on household attitudes to energy use of the adop-
tion of microgeneration technologies like solar water
heating, microwind turbines and air source heat pumps
[21].
The OU/EST surveys provide evidence from a repre-
sentative sample of adopters and a purposive sample of
potential adopters and nonadopters of microgeneration
heat technologies that can inform government policies,
industry strategies, and specifications for usercentred
design improvements that should encourage the uptake of
microgeneration heat and so make a significant contribu-
tion towards achieving the UK’s carbon reduction tar-
gets.
5. Acknowledgements
This article summarises part of an Open University (OU)
and Energy Saving Trust (EST) project that aims to eva-
luate low and zero carbon microgeneration heat tech-
nologies for UK households, funded by the Higher Edu-
cation Innovation Fund’s ‘Carbon Connections’ pro-
gramme and the EST. The authors wish to thank all those
who contributed to the project, especially Jennie Abel-
man, Rosalyn Dungate and Simon Green of the EST. It
builds on previous OU research on consumer adoption of
household renewables and forms the background for the
field trial evaluation by the EST and OU of heat pumps
in real UK domestic installations, the first phase of which
was completed in September 2010.
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