Windows and the Code for Sustainable Homes

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
• Water
• Materials
• Surface water run-off
• Waste
• Pollution
• Health and wellbeing
• Management
• Ecology

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. For a house to get six stars, it needs to collect 90 points or above.

Minimum standards are set for the two key areas within the design categories, namely energy and water use (see table 1 below).

For example, to achieve 3 stars for energy and water performance thermal performance must be 25% better than that determined by the 2006 Building Regulations Parl L and water must be no more than 105 l/p/d (litres per person per day).

Where government money is involved in the construction of new houses via The Housing Corporation (housing associations) or English Partnerships, there will be a mandatory minimum rating to be achieved of at least three stars.

The CSH is currently not mandatory on house builders to the private sector. However, the government hopes private house builders will use high star ratings as a commercial incentive to attract buyers and sell more houses.