TREND ANALYSIS
Below: High quality housing, complex design and performance are now at the top of housebuilders lists in terms of priority
calculation methodology for the calculation of energy performance of new buildings. This implemented Article 3 of the Energy Performance of Buildings Directive, "Adoption of a methodology", which requires the adoption of a methodology at either national or regional level for calculation of the energy performance of buildings based on a general framework. The 2006 changes to Part L
were intended to cut energy use in new homes by 20 per cent compared to a similar building constructed to the 2002 standards, and taken together with the 2002 changes reduced emissions from new homes by 40 per cent over the 1995 standard. These changes were driven by the long term aim of reducing overall emissions by 60 per cent by 2050, a target that has now been set at 80 per cent by 2050. Previous regulations considered calculation of the u-value as the primary measure of energy efficiency. Since 2006 a Dwelling Carbon Dioxide Emission Rate (DER) calculation is required, which estimates carbon dioxide emissions per m² of floor area. DER is calculated using Government's Standard Assessment Procedure (SAP) for Energy Rating of Dwellings. In addition to the levels of
insulation provided, the DER also takes account of the airtightness of the building, efficiency of space and water heating and the lighting, together with any savings from solar power or other renewable energy
generation technologies employed. It is a calculation based on the overall design of the home and the systems within it.
Some organisations raised
doubts over the claim that these changes would result in a 20 per cent emissions reduction. Issues cited included alleged problems with the calculation methods, the limitations of the software, and the specification of the reference building used in the model. One example, which fuelled such concerns was a 2005 study sponsored by the Pilkington Energy Efficiency Trust, which indicated that the savings would only be in the region of nine per cent.
“Much work has been
done to answer the questions about what a “zero carbon” home might look like, and how it would be specified in the Building Regulations.”
Meanwhile, much work has
been done to answer the questions about what a “zero carbon” home might look like, and how it would be specified in the Building Regulations. Until the early part of 2011, the whole industry was still working on the understanding that both the regulated energy uses (heating, fixed lighting, hot water
and building services) and unregulated energy uses (for domestic appliances) would be taken into account in the overall definition of ‘zero carbon’. On this basis, over a year there would be no net carbon emissions resulting from the operation of the dwelling, with net emissions from use of electricity to heat or power the building would be offset by the saved emissions from on-site energy generation. This on-site generation would be achieved either through measures installed in or on the individual dwelling or through site wide strategies. The sector was preparing to provide super low energy construction; teaching the supply chain how to build in an energy efficient way, and through the use of on site renewables. However, in March of this year
the coalition Government’s budget announced that Government will hold housebuilders accountable only for those CO2 emissions that are covered by Building Regulations”. This presented the housebuilding industry with an unforeseen predicament. The announcement set housebuilders an overall carbon reduction target one third less challenging than previously expected. Whilst this implies lower costs for house builders, it upset those looking for stringent carbon targets and those in the industry who had been doing most to gear up for the more challenging target. Interestingly, it was reported that many large house builders accepted
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