Towards Zero Carbon Homes
As a pure energy efficiency measure, Energy Performance Certificates were introduced on 1st August 2007 under the Energy Performance of Buildings Directive. These will be a mandatory requirement for all new homes and other homes when sold or leased by 2009. Energy performance certificates will be required to be provided at the point of purchase or sale.
Energy Performance Certificates tell you how energy efficient a home is on a scale of A to G and also how much that home impacts on the environment.
Better rated homes have less impact because they have fewer carbon dioxide emissions.
The Code for Sustainable Homes (CSH)
On a broader level, the government has introduced the Code for Sustainable Homes as from April 2007 (effective in England only at this time) and this code is to form the basis for future Building Regulations in relation to carbon emissions and energy use. It goes beyond energy performance measured but energy performance is central to the CSH.
Star Ratings
The Code for Sustainable Homes is based on a star rating system. One star is the entry level, which is recognised as higher than the existing minimum in the current Building Regulations. Six stars are currently designated as the highest level achievable.
Design Categories
There are nine identified design categories within the Code for Sustainable Homes, each of which obtains up to a maximum of six stars. These are:
- Energy
- Pollution
- Water
- Health and well-being
- Materials
- Management
- Surface water run-off
- Ecology
- Waste
Builders can pick and choose between the nine design categories to gather points under each heading towards achieving a star rating for the whole house.
Star ratings are calculated on a points-out-of-one-hundred basis across the nine categories, namely energy and water use.
Solutions from Global Home Improvements
Because Global PVC windows and doors can be provided with exceptional weather tightness and energy performance, using specialist glazing and construction methods, they can be central towards the achievement of a zero carbon home which requires a category six under the energy element in the Code for Sustainable Homes.
Global triple glazed windows, for example, can achieve an ‘A’ rating under the DWER calculation system (Domestic Window Energy Rating), incorporating enhanced thermal features such as Thermlock™ reinforcement, exceptional weather tightness and several separated structural chambers within the profiles (four and five) giving improved thermal efficiency.
Global PVC windows and doors play a key role in specifiers and users achieving a six star rating under the energy category and hence towards the objective of obtaining a zero carbon home.
BRE Green Guide
As far as the materials category is concerned in the Code for Sustainable Homes, at least three of the following five elements must be rated ‘D’ or better in the revised BRE Green Guide. These are roof structure and finishes, external walls, upper floor, internal walls, and doors and windows. The Green Guide published by the BRE is used to give material ratings covering all building materials and this is based on a range of sustainability criteria devised by the BRE.
Points are awarded for each of the elements being rated ‘B’ or better.
Therefore, the thermal performance of windows and doors is far more important than the material from which they are manufactured.
For example, the difference between the use of ‘A’ and ‘B’ rated windows under the materials category is 0.3 points. This is negligible, when it is a total of 90 points that is required to achieve a six star rating.
Sustainable Materials
The manufacturers of the PVC used by Global Home Improvements, has an accredited Environmental Policy and is kitemarked to EN 14001. In addition, these PVC products are easily recycled through a large nationwide system of collection and reprocessing.
Global PVC products are also calcium organic stabilised with our manufacturers being the first UK extruder to eschew the use of lead based stabilisers.
Great benefit can be obtained via concentration on a window’s thermal performance. For example, 1.2 points can be obtained for windows which perform only 10% better than the 2006 Building Regulations Part L. Global PVC windows can readily obtain a 20% improvement on current Part L values, depending on build specification. Such a performance improvement will yield 2.4 points toward the CSW totals.
High performance windows such as those rated above ‘C’ in the DWER energy rating system, which not only deals with U values but air tightness and solar gain, have an important part to play in the overall thermal performance of the house. Materials in isolation, however, have only a minimal impact on the total code points scoring system.
In comparison to the maximum points of 0.9 obtainable under the materials design category, for example, you can obtain up to 2.4 points as a housebuilder or designer from the provision of cycle storage, or 2.4 points for the provision of dedicated energy efficient security light fittings and 2.4 points where 75% of internal light fittings are energy efficient.
