The Code for Sustainable Homes (CSH) is the national standard in the UK that stimulates the construction of sustainable housing. It operates a star system, wheree six stars represent the most sustainable projects. Many local planning authorities in England require that a certain number of CSH stars are achieved, even for development proposals that comprise only one unit. This article explains the specialist input required for a CSH project and provides a suggestion to manage this effectively. Project managers / architects and their clients should be aware of these in order to meet these planning requirements without undue delay and cost.

Specialist input required
At the outside of the project one should be aware that a small team of sustainability specialists is required. As a minimum there are three specialties required:

  1. A formal CSH assessment is required to receive a certificate with the achieved rating. The assessment can only be carried out by a licensed CSH assessor.
  2. A licensed SAP assessor will be required to produce the energy efficiency calculations for the building. This is also a requirement for the building regulations and therefore not additional to a CSH project.
  3. A hydrologist report is required to demonstrate compliance with the minimum requirement related to drainage design.

These three specialties are the minimum required specialist input. Depending on the site and the sustainability measures that will be selected for implementation, additional specializations may be required. Typically these include an ecologist, a specialist in daylight factor analysis and an acoustic specialist. The need to appoint these specialists is project specific and depends on the selection of sustainability issues that will be chosen to be implemented. To ensure that the process of appointing these specialists does not cause undue delay to the progress of the project and increase the budget to unviable levels an early identification of the identification of the sustainability measures that is essential.

Early start
It is important that thinking about which measures to implement starts as early in the project as possible. There are a number of key items that significantly affect the CSH rating. Items similarly energy strategy and water strategy may involve considerable cost and design time. Also when ecology credits are expedient to achieve the required CSH rating a specialist ecology report may be required. This report needs to be prepared based on a site visit that is carried out before any work (including site preparation) has started on the site. Other issues may have an effect on the construction contract that needs to be drafted. I therefore typically promote the following steps in a CSH project:

  • Option analysis, where an initial assessment about the feasibility of each of the CSH issues are examined
  • Development of energy, water, materials and construction management strategies
  • Pre-assessment, where the final list of sustainability measures is agreed
  • Design stage assessment
  • Post construction review

Only the last two stages are formal and lead to a certificate.

Identifying the menu of sustainability measures
When considering all the items in the CSH manual, the project team should start with identifying the easy wins. Only a small number of items within the code are mandatory; most items are what is referred to as tradable. The design team has the freedom to select the items that would add up to the required rating. Depending on the characteristics of the project, some credits can be achieved by default. For instance in the second issue in the health category the code awards credits where the noise insulation between adjacent properties is better than the minimum requirements in the building regulations. Detached properties can claim the maximum number of credits in this issue by default. Other credits are so easy and cheap to realize that there is not much discussion about their inclusion. This is for instance true for energy-efficient lighting or providing a drying-line for laundry.

Once the default credits and easy wins have been identified the design team has an indication of the shortfall in credits. This allows for the targeted development of strategies around the big-ticket items such as energy, materials, water use, construction management and ecology. These items need careful consideration: they represent a large number of credits but may have a significant in the cost of the project or its management.

Once the strategies have been developed and decisions about which sustainability measures to implement have been made the pre-assessment can be prepared as a road map for the formal assessment stages. It is at this stage that the list of specialist input that is required for the project has been defined with a reasonable certainty. This also means that at this stage a reasonable estimate of program and budget needs can be made.

So, in short, this article explained that some items on the CSH menu of sustainability measures require specialist input. The nature and amount of specialist input is project specific. As appointing specialists may add to the duration of the project's program and require additional financing it is essential to consider all the sustainability measures that will be implemented at an early stage.