Energy use in buildings
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Energy use in poorly insulated buildings is a major contributor to energy wastage. However, there are problems with changing this situation. New buildings can be designed properly to avoid energy waste, but the rate of new build is relatively low, so it will take a long time to make an impact. For example, around 60% of UK housing stock is the so-called ‘heritage building’, including many old houses whose owners do not want them changed radically. Certainly few would back whole-sale demolition, even if much of it is very poor in energy performance terms. There are energy retrofit/rehab options for some existing and refurbished buildings. But it is not always easy to assess the real-world cost effectiveness of energy efficiency upgrade measures. Indeed, some say that in some situations it is more expensive to rehab an old building with insulation upgrades than to link it to a district heating (DH) network fed by a Combined Heat and Power (CHP) plant, if that is available. It is easy to see how it could be hard to upgrade high-rise buildings without major effort (e.g. new exterior cladding), but a study by Orchard Partners for the UK Technology Strategy Board, ‘Retrofit for Future’, comparing CHP/DH with domestic insulation concluded that, even for a typical late 1960s/early 1970s London houses in a terrace of five houses, connection to DH gives a lower capital cost per tonne of CO2 displaced than alternative insulation measures (Orchard Partners 2008). So, for some old buildings it may be possible to save more energy at less cost by linking up to DH networks than by rehabbing them with retrofitted insulation: put simply, it is cheaper to insulate a DH pipe than a difficult building. That view was backed up by a major report on CHP/DH for the European Commission by the EC Joint Research Centre, which concluded that that CHP/DH has a lower capital cost/tonne CO2 saved than renovation (JRC 2014). At present, most CHP/DH uses fossil fuel and although CHP is very efficient (reducing emissions/kWh of total energy output by over a half and possibly much more), increasingly use is being made of lowor zero-carbon renewable energy sources like biomass and even in some locations soar with large heat stores. Of course, not all houses are in cities or near existing or planned DH networks, so, there, opportunities for cost-effective energy saving upgrades exist. Indeed, some simple upgrades make sense even if DH is available and used. It is basically a trade-off situation, looking for the optimal practical mix. City-wide or even local DH is expensive and invasive to install in streets, so if DH does not yet exist nearby, insulation upgrades will often have the edge: depending on the site, they can be quicker and cheaper to install. That said behavioural change may be an even cheaper way to reduce energy use. A nice slogan adopted in one national campaign was ‘if you sing in the shower, choose shorter songs’. The emphasis in this sort of approach is on the energy used in devices, for heating, lighting and so on. And that use can be reduced technically, as well as through changes in use patterns. In the UK, Department of Energy and Climate Change (DECC) says that the costs of household appliance use have fallen by up to a half in some cases, due to the various device efficiency upgrades/standards (DECC 2014). However, behavioural change may still have the edge. A US study found that, in some test cases, behavioural changes were as effective in energy terms as technology change (an upgraded fridge), but might be cheaper (UCE3). Even so, there are limits – behavioral change may be resisted or abandoned over time. Supplying the energy from ‘green’ sources, either on the building (e.g. roof top solar), in the building (e.g. heat pumps) or brought in on the grid (e.g. from large remote wind farms), may not be cheaper, but, like plugging into a DH network, it involves no changes in consumer use patterns, or significant changes to the house or installing disruptive upgrades to the building envelop. By contrast, green energy supply ‘technical fixes’ are inevitably going to be popular with consumers, since they avoid disruption and having to make lifestyle changes.