HEAT PUMPS 2 CLIMATE CHANGE
buildings) would facilitate the installation of equipment to clean flue gases and maintain urban air quality. Alternatively, these schemes could be
supplied by large heat pumps which draw heat from under a local park or other open space. A third option is that they could be supplied with heat from grid power stations; past studies have shown that this could be a viable option even if the station were 50 to 100 km away.
Heat pumps can have a significant role in leafy suburbs
central areas of towns and cities, which have high-density housing such as 19th century terraces, and extensive areas of non-domestic buildings, needs to be established.
Urban heat supply If heat pumps serving individual buildings are not feasible in urban areas, other options
will need to be considered. These include: l Direct electric heating; l Combustion of biogas; l Communal heating schemes; and l Currently unproven approaches such as
distribution and combustion of hydrogen. Each of these presents challenges. As noted
above, direct electric heating would require a large increase in supply capacity. Scenarios such as the construction of a new mega-grid that would supply Europe with electric power generated from photovoltaic (PV) arrays in North Africa might provide such capacity, but these remain speculative. Similarly, the sustainable level of energy
Achievement of the 2050 target requires the built environment to be effectively decarbonised by that date
production from biomass remains unproven. The Renewable Energy Review notes that there are limits to sustainable biomass and that it may be preferable to use biogas (and biomass generally) to reduce emissions from industry rather than from buildings. The CCC intends to publish an assessment of biomass later this year. The economic viability of communal
heating schemes depends on the ‘heat density’ of the areas served, which will be lower in the future because of energy efficiency measures in buildings and the rise in average winter temperatures as a result of climate change. Such schemes could draw heat from local biomass-fired boilers or CHP plants, where the larger scale of operation (as compared with boilers for individual
36 CIBSE Journal August 2011
Conclusions While most attention is currently focused on measures that will reduce the demand for heat in the building stock, these will not remove the need for housing and other buildings to be supplied with heat. Decarbonisation of the built environment will therefore require a combination of demand-side and supply- side measures. Heat pumps supplied by decarbonised electricity will undoubtedly have a significant role to play nationally, but this may be limited in highly developed urban areas. Land use, which is a key responsibility of
local councils, could become an important factor in future energy supply. Communal heating plant based on biomass would need to be located conveniently to the area served, with due allowance for storage of fuel. Perhaps new open areas will need to be created, both for energy supply needs and to improve the local urban climate. If heat is to be imported from distant power stations, suitable supply corridors will need to be protected. Energy supply may therefore become a
matter for strategic planning at the city and town level, rather than the national level – almost a return to a previous era when municipalities invested in gas works and electricity generating plant. Similarly, there are potential implications
for the new power stations required over the next two decades. It will be important to establish whether these, like their predecessors, will be confined to supplying electricity, or should also supply heat. A programme of studies is therefore
needed to establish the relative technical and economic merits of the different options for heat supply to urban areas, against the background of the overall emissions targets to which the UK is committed.
l roger courtney is professorial research fellow, Manchester University, and visiting professor, School of Construction and Project Management, University College London
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