The Code for Sustainable Homes is an environmental assessment method for rating and certifying the performance of new homes in England, Wales and Northern Ireland. It is a national standard for use in the design and construction of new homes with a view to encouraging continuous improvement in sustainable home building.
The code works by awarding new homes a rating from Level 1 to Level 6, based on their performance against 9 sustainability criteria which are combined to assess the overall environmental impact. Level 1 is entry level above building regulations, and Level six is the highest, reflecting exemplary developments in terms of sustainability.
The sustainability criteria by which new homes are measured are:
The Code is a 6 level rating system with credits in a broad range of categories from water use to occupant health. There are simple and inexpensive methods of gaining credits, like specifying compost and recycling bins, and costly methods such as installing solar photovoltaics.
Currently, compliance with higher levels of the Code is voluntary, with a long-term view for step-change increases. However, landowners and agents are already selling sites with stipulations to build at a certain Code level.
The extra-over cost of building to Code Level 3 is valued between around £2000-3000 when averaged across a large development, additionally the Code assessment costs around £4000 for a small project, the total cost of this is typically over 4% of a standard build, and when taken in hand with local authority fees for “blackmail” clauses can well end up with 75% of any equity being “taken” from the developer, but this is made light of in official government publications 
Code levels pertaining to energy require a Dwelling Emission Rate (DER) a certain percentage lower than the Target Emission Rate (TER) as set in Part L1A of the Building Regulations. The October 2010 version of the Code saw Part L 2010 TER standards rise equivalent to Code Level 3. Since this change Code Level 4 requires 25% DER improvement over Part L1A 2010 TER standards and Code Level 5 requires 100% improvement i.e. thermally twice as efficient. It is also anticipated that the Building Regulations as well as the minimum mandatory Code level will continue to improve until the 2016 target of ‘net zero CO2 emissions’ is met. Guidance is also available via the Code’s simply explained published document to clarify the technical requirements.
Goslin & Co advise with UK Building Regulations including supporting information for Sustainability statements, Code assessments and Appendices for Planning Compliance. We also provide a design service visualising your project with planning and building regulation drawings and with the eco-designer add-on for Archicad this includes 3 dimensional visualisation.