Practice



SUSTAINABILITY
New Code
Extensions & Conversions
Building Regulations
HIPS
Practical Application
Collectors
Materials
Insulation Theory


New Code

New Houses		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: Energy Water Materials Surface water run-off Waste Pollution Health & Well-being Management Ecology 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
Extensions & Conversions

		Existing houses with new extensions are not specifically covered by the Code for Sustainable Homes, though it provides a standard to be aimed at. In practice bringing the existing housing stock up to the level of the current (2006) Building Regulations is a huge challenge in itself.


Building Regulations
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Listed Buildings		Extensions & Conversions are covered by Part L1b of the Building Regulations 2006 which define standard thermal insulation standards and limit the areas of glazing to 25% of the new floor area plus the area of any windows and doors. Conservatories have to be thermally separated from the dwelling. 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. Construction has to comply with Accredited Details. These are completed by the Site Manager (usually the Contractor) and submitted to Building Control. Complying with these details ensures that the insulation is correctly installed and that the building is kept air tight. Listed buildings are generally exempt - and getting permission to insulate existing buildings is difficult. To save energy you need to wear more jerseys!
HIPS
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		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. Access full information by clicking on link: http://www.homeinformationpacks.gov.uk/consumer/

Energy Efficiency Rating		These are an integral part of the HIPs and are assessed using approved software based on a calculation procedure called SAP 2005 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. Use of collectors such as panels for solar water heating, photovoltaics and other energy collectors are included in the calculated assessment. 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.
Practical Application
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		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 as much energy as possible - but where there are limited funds then a balance has to be struck. 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 mineral fibre 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/ Warmcel/real wool 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 low-impact summerhouse was insulated with Tri-Iso Super 10 - in part to test the new technology as well as the use of local timber, FSC products, minimal foundations and high performance multi-foil insulation. Early signs are impressive both at keeping heat in as well as out on hot days.

Collectors
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Solar panels		Solar panels for heating water is now well established technology In 2005 solar panels were installed at 7 Hill Top Road and have proved to reduce hot water heating bills significantly over the passed two years.

Ground Source Heat Pumps		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.
Wind Power		Still a long way to go - particularly in an urban environment. Practically will probably only be cost effective at larger scales.

Rainwater Collection		Worth serious consideration if all the plumbing is being redone. A parallel plumbing system is required for flushing loos with a separate tank in the loft. Water storage is calculated on usage, rainfall and roof area. No ground water can be included because of contamination.

Materials
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		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.


Insulation Theory
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		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. Click on graph to left for special section.

Disclaimer		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.