The Sustainability Rating System

The Code uses a sustainability rating system – indicated by ‘stars’, to communicate the overall sustainability performance of a home. A home can achieve a sustainability rating from one (*) to six (* * * * * *) stars depending on the extent to which it has achieved Code standards. One star (* ) is the entry level – above the level of the Building Regulations; and six stars (* * * * * *) is the highest level – reflecting exemplar development in sustainability terms.

The design categories considered are

  1. Energy
  2. Water 
  3. Materials
  4. Surface Water Run-off
  5. Waste
  6. Pollution
  7. Health and Wellbeing
  8. Management
  9. Ecology

Mandatory minimum performance standards are set for some. For 4 of these, a single mandatory requirement is set which must be met, whatever Code level rating is sought. Credits are not awarded for these issues. Confirmation that the performance requirements are met for all 4 is a minimum entry requirement for achieving a Level 1 (*) rating.

The 4 un-credited issues are:

  1.    Environmental impacts of materials
  2.    Management of Surface Water Runoff from developments
  3.    Storage of non-recyclable waste and recyclable household waste
  4.    Construction site waste management.


If the mandatory minimum performance standard is met for the 4 un-credited issues, 3 further mandatory issues need to be considered. For two of these, credits are awarded for every level of achievement recognised within the Code, and minimum mandatory standards increase with increasing rating levels.

The two issues with increasing mandatory minimum standards are:

  1. Dwelling emission rate

  2. Indoor water use


The final issue with a mandatory requirement for Level 6 of the Code is:

  1. Lifetime Homes


The table below shows the nine design categories and the degree of flexibility afforded by each category.

  Flexibility of the Code


Energy/CO2

Water

Minimum standards at each level of Code

Materials

Surface water run-off

Waste (household)

Waste (construction)

Minimum standard at Code entry level

Pollution

Health & Wellbeing

Management

Ecology

No minimum standards

 Calculating an Assessment Score the assessment process should proceed in a logical order through the environmental impact categories and issues, summarised in below:

  • It should begin with a check that the 4 mandatory issues for which no credits are awarded have been achieved:
  • The mandatory credits for CO2 emissions and for internal water use should be checked and confirmed at the minimum values required to meet the Code level sought.
  • The remaining tradable credits should be checked and confirmed so that they too contribute to the required Code level.
    If any of the standards for the four non-creditable issues are not met, then a zero rating will result, regardless of the other credits achieved, including the creditable mandatory issues.
  • If all the non-creditable mandatory standards are met, but one or other of the creditable mandatory issues fails to reach the minimum for a higher required level, the rating achieved will be determined by the lowest level which all the mandatory issues meet.
   
   
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