by Dave Elliott
‘40% of Europe’s energy use and a third of the greenhouse gas emissions can be attributed to buildings and much of this relates to heating and cooling. For example in the UK, 38% of all CO2 emissions are related to space heating. These emissions can be avoided or significantly reduced through a combination of holistic design, integrated renewable energy and high efficiency.’ So says a report on Sustainable Heating and Cooling of Buildings from Leonardo Energy, the European Copper Institute’s think tank, offering a good analysis of the options for reducing buildings’ energy consumption and carbon emissions.
The report puts the options in the following order of priority:
1. Reduce heating and cooling loads
a. Optimise the building fabric to reduce the need for heating and cooling
b. Minimise internal heat gains through selection of efficient lighting, equipment and processes
2. Incorporate passive solutions in the building design
3. Maximise the energy efficiency of installed systems
4. Capture and use renewable energy
The report provides an overview of the technical opportunities to reduce energy consumption in buildings by implementing sustainable heating and cooling. There is less said about standard building design-related energy saving measures: the report assumes that all new buildings will be constructed with a good standard of fabric insulation in accordance with the local implementation of the EU Energy Performance of Building Directive (EPBD), but it insists that ‘ for existing buildings the possibility of fabric improvements should always be considered before investments in new heating and cooling technologies’.
Part 1 looks at alternative low and zero carbon technologies for heating and cooling that should be considered for new buildings and major refurbishments – including passive and active solar, heat stores, heat pumps, fuel cells, biomass fired heating and micro-Combined Heat and Power (CHP) units. It doesn’t get into the wider debate about whether larger-scale CHP feeding district heating networks are a better option for cites; it’s focus is on in-house installations. Also, heat pumps apart, it does not look at the use of electricity for heating and cooling, which is odd since it may be that domestic PV solar could play a role in the latter, being well matched to daytime summer air conditioning. But that opens up the wider debate as to whether using grid-linked green power from larger more efficient wind farms or whatever is a better option than in-house micro gen. All it says is that, in some remote locations, small wind turbines can be used for heating. But it’s good to see absorption and adsorption/evaporation chillers given special attention, including solar power variants: that could become a big new issue as climate change hits. See my last post.
Part 2 of the report looks at improving the operation and performance of existing houses via upgrades and retrofitting. For some UK examples see www.lowenergybuildings.org.uk/projectbrowser.php?fmd=0. And for a Technology Strategy Board overview: www.innovateuk.org/retrofit-analysis.
Rehab/retrofit is obviously a wise first response in many cases, but there have been some studies that suggest that, for some buildings (e.g. high rise flats or even old terraces), retrofitting insulation cladding and similar upgrades can be more expensive/kWh than installing more efficient heating systems or linking into district heating networks, if they are available locally. For example, a 2010 study ‘Retrofit for the Future’, by Orchard Partners for the UK Technology Strategy Board, comparing CHP/District Heating with domestic insulation, concluded that, even for a typical late 1960s/early 1970s London terrace of five houses, connection to district heating gave a lower capital cost per tonne of CO2 displaced than alternative insulation measures. For more on the merits of CHP/DH see: http://setis.ec.europa.eu/system/files/JRCDistrictheatingandcooling.pdf.
Although there are thus some strategic issues that have been left aside, overall it does seem clear that, as the Leonardo report says, ‘ from comparisons of building performance across Europe that there is enormous scope for reducing the energy consumption of buildings by improving design and implementing the “best available technology not entailing excessive cost”. However, we should not forget the human factor. A large part of the energy consumption any building is determined by the behaviour of the building occupants. The best technologies will not achieve the best result unless the occupants understand how the building is supposed to work and are committed to making it work.’ www.leonardo-energy.org/good-practice-guide/sustainable-heating-and-cooling-buildings
That last point was reinforced by a study a while back, based on two small research projects, which found that occupant behaviour was as important as technology in determining the energy used by a household. Householders who were trained in how to maximise the energy-saving benefits of their houses generally used considerably less energy than those who did not, while permaculture practitioners had an environmental footprint considerably lower even than those who lived in purpose built eco-homes. Thus housing policy that focuses solely on technology may be missing an important factor in energy efficiency. ‘Relative benefits of technology and occupant behaviour in moving towards a more energy efficient, sustainable housing paradigm’ Pilkington B, Roach R, Perkins J (2011) Energy Policy, Vol.39, No.9, pp.4962-4970.
There is no question that, however it is generated, avoiding energy waste makes sense, environmentally and economically, and buildings use the most energy. So it is good that the International Energy Agency is now on the case, with energy saving being pushed as a key global strategy. For example, see the IEA’s ‘Transition to Sustainable Buildings’, report: www.iea.org/w/bookshop/add.aspx?id=457 and this good practice guide: www.gbpn.org/reports/best-practice-policies-low-carbon-energy-buildings-based-scenario-analysis.
Whether these high level aspirations will trickle down to affect local building practice and consumer behaviour remains to be seen. In the UK, the Green Deal commercial loan scheme for domestic sector energy saving upgrades is meant to be a central initiative, but so far it has been pretty ineffectual. Looking further ahead, the government has set a 6% carbon reduction target for new build homes and a 9% cut for non-domestic buildings, compared to 2010 levels, to come into force next April. It’s part of their revamp of the watered down ‘zero carbon’ standard for new build by 2016. There seems to be a slight shift away from single house focus, with options including the use of heat networks, and offsetting via third party ‘allowable solutions’ in which developers invest in offsite projects to deliver carbon abatement on their behalf. But domestic heat pumps are still seen as a key element.
In its earlier studies the Energy Saving Trust (EST) had identified problems with heat pumps used in the UK, but the performance and efficiency of heat pumps has improved substantially, according to a new EST study, who now say that homes best suited for heat pump installations could earn savings and income of around £1350 a year on air source heat pumps and around £3000 a year on ground source heat pumps. www.energysavingtrust.org.uk/Organisations/Working-with-Energy-Saving-Trust/The-Foundation/Our-pioneering-research/The-heat-is-on-heat-pump-field-trials
With the domestic Renewable Heat Incentive (RHI) now started up, householders could get paid 7.3p/kWh for air source heat pumps and 18.8p/kWh for ground source heat pumps. 400 council tenants are already to benefit from the installation of air source heat pumps in Stroud under the existing Social Landlords RHI Payment scheme. There are smaller projects like this elsewhere. Whether other domestic scale green heat supply options, like solar and biomass, will also prosper remains to be seen. Add-ons like this do have their appeal, but it’s good that the new RHI support schemes include a requirement for attention to energy saving measures as a prerequisite. That may help energy saving to be taken seriously in practical, on the ground, projects, not just in reports.
Certainly there is a lot that can be done at the grass roots in many areas of green energy supply and energy saving, as my next two posts explore.