BRE IP6/13 PDF

Introduction

The Code for Sustainable Homes (CSH) is an environmental assessment method for domestic dwellings. As a Government standard it is developed, owned and operated on behalf of the Department for Communities and Local Government (DCLG).

The CSH criteria were initially based on BRE's BREEAM EcoHomes Technical Guide^[1]. The CSH was officially launched in England in 2006, with the first technical guide being released in March 2007. The EcoHomes technical guidance, was superseded by the revised publication The Code for Sustainable Homes Technical Guide published in 2007^[2] in respect of new build homes in England, Wales and Northern Ireland. The CSH is periodically revised to ensure it is kept in line with emerging standards and policies and has gone through several revisions since its launch, with the most recent release of the technical guide being the November 2010 scheme version.

The CSH provides a methodology for rating dwellings on a scale from Levels 1 to 6, with Level 6 being the most sustainable. In England, Wales and Northern Ireland where the CSH is used, Level 3 has been set as the minimum standard to be achieved for new self-contained social housing (where publicly funded). At a local level, many planning authorities are also setting CSH requirements for new housing developments.

The dwelling ratings given by the CSH are dependent upon scores achieved within nine environmental sustainability categories: Energy, Water, Materials, Surface Water Run-off, Waste, Pollution, Health and Wellbeing, Management and Ecology. Five of the sustainability categories include minimum standards which every CSH home must meet in order to achieve any rating, and one final category contains minimum standards specific to CSH Level 6 homes only.

Surface water run-off is one of the five categories where there is a mandatory requirement which applies for all versions of the CSH. This category consists of two issues:

• Sur 1: Managing surface water run-off from developments

• Sur 2: Flood risk.

Sur 1 is the issue which includes mandatory criteria. Any dwelling seeking to comply with the CSH must meet the Sur 1 criteria. This Information Paper will provide an overview of the mandatory requirements within the Sur 1 issue and highlight why the criteria are important and how to demonstrate compliance for all situations. It will also give an overview of the tradable credits relating to water quality within the surface water run-off issue (note that the detail relating to how credits can be awarded can be found within the relevant version of the CSH).

When the CSH was developed it was clear that managing surface water run-off was an important aspect of sustainability. Its importance was emphasised by the publication of Learning Lessons from the 2007 Floods (The Pitt Review) in 2008^[3]. The Pitt Review identifies the causes of the 2007 Summer floods in England, during which approximately 55,000 homes were flooded. It found that ‘surface water flooding was a major issue during the floods and will remain a significant problem in the future', something which the CSH Sur 1 criteria seek to address.

The floods in 2007 were a clear example of how the current drainage infrastructure struggles to cope with the increased demands placed on it by future urban development and climate change. Two thirds of the properties were flooded because the drains and sewers had been inundated by the Summer storms and were unable to cope with the demands placed on them.

The Building Regulations (Part H)^[4] require that provision is made for dealing with the increased surface water run-off from rainwater falling onto a new building's roof, and onto the paved areas around the building. It lists a hierarchy of three measures for dealing with run-off. The first is by using a soakaway or some other infiltrating Sustainable Drainage System (SuDS). Where this is not possible, run-off should be discharged to a nearby water course, or failing that, discharged into any available sewer. Beyond this, Part H gives relatively few details, stating that in each case ‘adequate' provision for rainwater run-off should be made, but no further guidance is provided. The requirements set out in planning are also often limited in detailed guidance, requiring a drainage strategy to be developed to manage the run-off from the site and ensuring agreement from all the relevant statutory bodies, eg the Environment Agency and the adopting water authority, in relation to the chosen drainage strategy.

To support the current regulatory requirements and assist industry in moving towards the forthcoming Floods and Water Management Act and the associated SuDs standards, Government policy will include surface water run-off as a mandatory requirement within the CSH as a precursor to the introduction of the Floods and Water Management Act[5]. Elements of this Act are being implemented and will eventually work in conjunction with the SuDS standards when they are released. The SuDS standards will provide guidance and encourage the implementation and adoption of SuDS.

(Note: The surface water run-off criteria in The Code for Sustainable Homes Technical Guide^[6] will be re-evaluated following the implementation of the Floods and Water Management Act and the National SuDS Standards.)