40 THE CLIMATE CHALLENGE
Overheating & bridging the ‘performance gap’
Among its many suggestions, the CCC’s ‘Fit for the Future’ report asserts that it is vital that homes be climate-resilient. One of the more obvious examples of climate change is rising temperatures, and as such, there is a rising necessity to improve the heat resistance of our homes, as well as to provide the necessary cooling. Overheating has been on the rise,
exacerbated by what The House Builder’s Association has termed ‘the ever-exacting standards’ of Building Regulations Part L, which stipulates airtightness levels that are argued to be too high without mitigat- ing measures. A warming climate will of course add to the problem.
In 2003 we experienced one of the most significant heatwaves recorded – more than 2,000 people lost their lives – but such events are expected to be the norm in summer by the 2040s. Another warning was given this summer, with France seeing temperatures of 45.9 degrees celsius, the highest ever recorded in the country.
According to the CCC’s report, 20 per cent of homes in England already overheat. It states, “In the absence of action,” annual UK heat-related mortality is projected to increase from a current baseline of 2,000 deaths per year to 5,000 per year by 2050 (or 7,000 if accounting for projected population growth.)
WWW.HBDONLINE.CO.UK
Unfortunately, there would still be around “41,000 cold-related deaths per year,” says the organisation. With the proportion of urban green spaces in England dropping from 63 per cent in 2001 to 55 per cent today, the ‘Urban Heat Island Effect’ will increase, further adding to already increasing temperatures in cities. While there has been some clarification
in the National Planning Policy Framework in England to address some issues foregrounded by climate change, such as overheating and flooding, the CCC report details that “the revisions have removed the requirement for local author- ities to give active support to energy efficiency improvements to existing build- ings, and have failed to clarify how far local and regional authorities are permit- ted to go in setting their own tighter standards for new-build homes.” There are many ways in which house- builders can combat these issues however, usually through insulation and various HVAC products. Ventilation and air condi- tioning are also obvious solutions – but often come with their own problems. As the industry well knows, as buildings have become more airtight and efficient in terms of heat loss, air quality has taken a hit. Air conditioning systems don’t generally provide ventilation, instead recirculating the air and running it through a cooling coil, though MVHR (mechanical ventilation with heat recov- ery) can provide a solution to this. Some air conditioning units can also be expen- sive to run, and, being energy-hungry, many units will significantly add to a home’s carbon output. ‘Passive cooling options’ are another potential way to mitigate this issue, with building orientation, shading, thermal insulation and construction materials all being factors to consider during the
design and build of homes that can prove extremely effective in reducing heat impacts.
As to insulation, while higher levels of insulation has historically contributed to the overheating of homes, research from the Building Research Establishment (BRE) has shown that providing thermal insulation to the walls and roof of a home can help to prevent solar gain through the structure.
Such design focused elements can be extremely potent at zero carbon cost, however, even when buildings are designed to be efficient and climate resilient, they do not always end up the case in practice.
THE PERFORMANCE GAP When discussing making homes more climate resilient, as well as efficient, it is important to remember that even now the building regs have been adapted towards reaching fossil fuel free heated homes by 2025 (as dictated by the Future Homes Standard 2025), there is a significant performance gap in energy usage between building design and operation currently. As raised by Dr Gavin Dunn from the Chartered Association of Building Engineers (CABE) in the June issue of Housebuilder & Developer: “The construc- tion industry has long grappled with the challenges of closing the performance gap between as-designed and as-built building performance.”
Dunn discussed how, since 2006, energy efficiency requirements were tightened within the Building Regulations and shifted towards a target of lowering carbon emissions. He said that subsequent step stages in both 2010 and 2013, related to the way that energy compliance is calculated, have “clearly changed the performance of new homes,” while having “unintended consequences” on our built
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76
