Hargreaves et al. (2016) developed a method of taking into account the variability of indoor and outdoor space of housing when forecasting the suitability of decentralized energy technologies. The research, published in the journal Applied Energy, substantially improves the spatial estimates of thermal energy consumption when compared to building energy models that use standard dwelling typologies. It also forecast how spatial planning scenarios would affect the suitability of decentralised energy supply.
The United Kingdom Future of Heating report by the government Department of Energy and Climate Change (DECC) proposed that decentralized energy supply, such as heat pumps and heat networks, will provide a large proportion of future domestic heating and make a substantial contribution to achieving future CO2 reduction targets. However, the DECC consultation on a domestic renewable energy incentive scheme identified costs and uncertainty about whether properties have the space for installation as important barriers. This leads to the need for the future built form characteristics and energy demands to be considered because they will affect the suitability of decentralized technologies and their uptake and cost effectiveness.
Research to carry out this investigation was part of a case study of London and its surrounding regions in the south east of England. It used urban modeling forecasts of the locations and average densities of dwellings for year 2031, and an innovative method of converting these densities into a representation of the housing stock and plot sizes. It thereby combined the regional simulation of urban form and building occupancies with the building-scale modelling of energy demand and supply to test combined scenarios for spatial planning policy, building regulations and technologies.
Dwelling energy demands were estimated using a Domestic Energy and Carbon Model (DECM) for predicting the energy consumption and carbon dioxide emission of the English housing stock. The decentralized energy supply options consisted of community-scale and building integrated technologies. Cost effectiveness was calculated as a relative measure against the most appropriate reference case and was used to explore the cost of achieving a one tonne reduction in CO2 emissions compared with paying a carbon price of around £ 70/tonne. The future costs and efficiencies of buildings and technologies were based on information available in 2009.
From the results, Hargreaves et al. (2016) showed that lower density areas would have the greatest potential for energy efficiency improvement by retrofitting because they would have a greater proportion of less energy efficient dwelling types such as detached and semi-detached houses. These would also have more garden and roof space for low carbon technologies that could partly offset their greater CO2 emissions. The integrated modeling framework showed how differences in the densities of dwellings due to spatial planning policies would affect their CO2 emissions and also the reduction in these emissions achievable by the energy supply systems.
The energy supply systems were selected based on the availability of suitable space, an initial estimate of their likely uptake, and sized with respect to their connected energy demand and operational characteristics. The results obtained show that the decentralized energy supply technologies would make only a marginal reduction in CO2 per capita for the case study regions in the forecast year of 2031 compared to conventional supply.
The UK has a policy to progressively de-carbonize the conventional energy supply and this will diminish the future CO2 reduction benefits of these local low-carbon technologies. None of the decentralized supply technologies tested, except micro-chp & gas, would be financially beneficial to households unless subsidized. Also, the new-build dwellings would be much more energy efficient and so would have less potential for further reduction in CO2 emissions by low carbon supply.
Hargreaves et al. 2016’s findings have helped to improve the evidence base for strategies on achieving carbon budgets and the results show that current strategies do not adequately take into account how future residential space constraints would affect the suitability of some of these decentralized technologies. Their future uptake is therefore likely to be lower than expected and is likely to decline unless there is continuing policy support. Also, they will become less cost effective at reducing CO2 when compared to conventional supply unless there is continuing improvement in their performance and costs characteristics.
Anthony Hargreaves1 , Vicky Cheng2, Sandip Deshmukh3, Matthew Leach4, Koen Steemers5. Forecasting How Residential Urban Form Affects the Regional Carbon Savings and Costs of Retrofitting and Decentralized Energy Supply. Applied Energy, Volume 186, Part 3, 15 January 2017, Pages 549–561.Show Affiliations
- School of Engineering, University of Birmingham, UK.
- Munich School of Engineering, Technische Universität München, Germany.
- Birla Institute of Technology and Science, Pilani–Hyderabad Campus, India.
- Centre for Environmental Strategy, University of Surrey, UK.
- Department of Architecture, University of Cambridge, UK.
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