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Sustainability |
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| New Code for New Homes
Extensions & Conversions
Building Regulations
Listed Buildings
HIPs
Energy Calculations
Practice
Solar Panels
Materials
Responsibility
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The Code for Sustainable Homes April 2007 introduces minimum standards for energy and water efficiency at every level. The Code measures the sustainability of a home against key design categories, rating the 'whole home' as a complete package. The minimum standards for Code compliance have been set above the requirements of Building Regulations. New homes can achieve a rating on a scale of one to six 'Code Levels' depending on the standard achieved. The key design categories included within the Code are:
Compliance with the Code is mandatory for publicly funded homes in England from April 2007, but is voluntary in the short term within the private sector. It is likely that compliance may become mandatory for all new homes in England as early as 2008. Download the guidance on http://www.planningportal.gov.uk/uploads/code_for_sust_homes.pdf Existing houses with new extensions are not covered by the Code for
When elements of the existing structure are being upgraded or replaced then they must reach minimum performance standards (U values see Advice). For example replacement windows must be double glazed. Listed buildings are generally exempt - and getting permission to insulate existing buildings is difficult. To save energy you need to wear more jerseys! There is no mandatory requirement to replace or upgrade the thermal elements of the existing house - unless there is a change of use e.g. outbuilding to kitchen. Upgrading will be achieved in the market through the use of Home Information Packs (HIPs). From the 10 September all 3 bedroom house coming on the market will require an Energy Assessment Certificate. http://www.homeinformationpacks.gov.uk/consumer/ These are an integral part of the HIPs and are assessed using approved software. These take into account not only the Thermal Insulation of the fabric (U-Values) - but also window areas, location and glazing. The type of boiler and fuel being used also plays a significant part of the calculations - so it usually pays to replace the existing boiler with a high efficiency condensing type.. The energy performance will then be shown as a Dwelling Asset Rating in two forms shown below:
The example above shows how an energy efficiency rating of 32 and environmental impact rating of 27 for a dwelling should be expressed. It is early days in assessing the cost/performance/added value of carrying out improvements to the existing fabric over and above that required by Building Control. Of course everybody wants to save the world - but where there are limited funds then a balance has to be struck. For instance: Ground Source Heat Pumps are well established for well-insulated buildings - but there is greatly reduced benefit in using them to heat uninsulated houses - much better to spend the money on insulating buildings first. Over the past 8 years replacing ground floors with insulated concrete floors and underfloor heating using water (not electricity) is standard in most extensions except those with suspended ground floors. Existing houses benefit from having external walls drylined - or if the cavity is sufficient filled with blown insulation - which is inexpensive compared with the benefits. External insulation acting as a building 'overcoat' is also very beneficial - but requires a rendered finish. Windows where possible are replaced with double glazed units as required by Building Regulations - using argon filled spaces and low-E surface treatment. Insulating roofs with additional rockwool/fibre glass/ Wamcell
insulation is also standard - though if loft spaces are to be used
for storage then better to insulate at rafter level - of which there are
several alternatives. The most recent being the use of multifoil
insulation - which requires careful detailing but for some products is
proven over long use and under test conditions. Our
The preference is to use materials from sustainable sources which can be reused. Timber form sustainable sources (in particular FSC - Forest Stewardship Council) is becoming widely used and available - and the cost premiums are reducing. Softwood is also covered by FSC certificates - which trace the timber back to a particular tree in a particular forest. Bricks in particular are high energy products which last for thousands of years - provided that the mortar used is not too strong. The project for David Ogilvy in London and the 7 Hill Top Road & 44 Chalfont Road both in Oxford has involved the use of recycled bricks where practical. For 12 years Richard Twinch specialised in research into uses of insulation products and how to avoid associated risks such as condensation using software that was developed in-house and which has continued to be used in practice for the past 15 years. The above notes are based on many years of consultancy, research & practice. It is given in good faith and is free. However, Richard Twinch & Richard Twinch Design Associates are not responsible for any work or design carried out following this advice. All design and specification should be checked by the relevant architects, engineers/statutory authorities before construction.
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