News
Client: BASF WALLTITE
Magazine: Housing Association Building & Maintenance, March 2011
Dual purpose insulation - an ideal solution for hard to treat homes
The UK has the oldest housing stock in Europe and the majority of these properties will still be standing and occupied in 2050. Despite targets to improve thermal efficiency and reduce carbon emissions in new homes, the replacement of existing homes is less than 1% per year. The result will be that at least 20 million homes will need to be improved over the next 40 years. John Bullen, Sales Manager - In-situ Insulation for BASF Polyurethanes explains the role that insulation has to play in improving both the airtightness and thermal efficiency of older homes.
According to the National Insulation Association (NIA), the UK housing stock of 24.5 million includes nine million with cavity walls which have not been insulated. A further seven million have solid walls that need insulating including solid brick, solid stone, pre-1944 timber frame and non-traditional construction while 13 million have 100mm or less of loft insulation compared to the 270mm required for new homes.
The potential for improvement depends largely on the age of the property. Houses built prior to the 1930’s were built with solid masonry walls, single-glazed windows and use solid fuel heating, often with no loft and no connection to the gas network, making it expensive to improve. One of the easiest ways to increase energy efficiency in these hard to treat homes, other than replacing the boiler, is to improve the insulation and airtightness which significantly reduces the thermal transmission of a property. This is very much in line with the BRE’s strategy to put ‘Fabric First and improving the fabric performance of housing in these ways is therefore top of the agenda for housing associations to achieve a successful and sustainable refurbishment project.
For small dwellings where internal space cannot be readily sacrificed, a high performance insulation material of minimal thickness is the best option. In-situ applied close cell insulation can be installed from within the building structure to seal and insulate hard to treat areas, such as windows, doors, parapets and soffits to create insulating air barrier system continuity from the foundation up through the walls and across the roof. The limiting value of 10m3/m2/hr@50Pa set within UK Building Regulations is easily achievable when using such insulating systems. This contributes to improved energy efficiency, reduced moisture transmission, reduced chance of mould and mildew growth and meets the new part L regulations in a single application.
In order to make a building truly energy efficient, a reasonable level of airtightness is vital. The benefits of improved insulation levels and more energy efficient heating systems are lost if warm air can leak out of a building and cold air can leak in. Up to 40 percent of conditioned air escapes through the cracks, gaps and holes that exist in the envelope of the average UK building. Continuous air barrier systems reduce air leakage by up to 83 percent, with associated potential gas savings of greater than 40 percent and electrical savings greater than 25 percent.
Spray applied polyurethane foam such as WALLTITE® achieves maximum U-values for minimum depth of insulation and completely seals against unwanted air leakage. On-site sprayed or injected polyurethane foam seeks and seals all gaps. Therefore no costly corrections for air gaps are necessary in the calculations. Timber frame and masonry cavity wall constructions insulated with polyurethane foam applied to the roof and walls have achieved air permeability results of 3m3/m2/hr@50Pa.
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