Code Assessment Processes

Choosing an Assessment Process to suit Project Timescales

The Code for Sustainable Homes measures the sustainability of a new home using nine categories of environmental impact. It employs a star rating system of six levels to communicate the degree to which the home is sustainable. Houses and flats can both be assessed. Minimum standards are set for energy and water use at each level.

The Code offers builders a tool with which to measure and benchmark their sustainability, provides valuable information to home buyers, and accelerates the construction of sustainable dwellings.

The categories of sustainability are sub-divided into a number of specific “issues”, e.g. the External Lighting issue comes within the Energy category. There are over 30 of these issues. Each one is assessed and credits are awarded when all the criteria are met. Documentary evidence must be collected to support each credit.

Issues are weighted according to their relative environmental impact. The percentage score (or “points”) for an issue is equal to the number of credits awarded multiplied by the weighting factor for that issue. The total points score along with performance in mandatory elements combine to form the final rating.

The processes outlined below should be adapted to suit the Client. Defining what each party expects of the other is highly recommended. Detailed discussion before engagement or at the early stages of a contract, particularly with a new customer/supplier relationship, reduces the risk of misunderstandings and consequent project stalling.

Preferred Process

Pre-Assessment

Up to (and including) Detail Design stage it is generally better to adopt the process outlined below as it is geared to maximising the score. It also avoids redesign work, late design changes and the retrospective gathering of evidence.

1. Pre-Assessment
In this process the aim of pre-assessment is to influence the design, including the development specification and drawings, such that the required rating is achieved. All pre-assessments should include a plan to achieve the target rating, taking account of scoring on each issue. This plan will alert the design team on the features they may need to include.

1.1. Site Issues (up to Scheme Design stage)
Start off by examining those issues which are determined by the site, especially ecology. If an ecological survey is to be carried out, it is worth considering whether to extend it to encompass the Code requirements. If one has already been completed the ecologist may be able to extend it with very little extra work. If a survey is not envisaged and the site has not yet been disturbed, the assessor can advise on the cost-effectiveness of commissioning one.

Renewable energy and water recycling (if required), and drainage, are also considered at this stage.

1.2. Basic Design (up to Scheme Design stage)
As the basic design is formulated, discuss issues such as:
• land use
• security
• Lifetime Homes
• daylighting
• materials and construction
• insulation
• SAP ratings
• heating systems

1.3. Detailed Design, and Construction Process (up to Detail Design stage)
While the details of the design are being put in place, finalise the specifications to ensure the required rating is achieved.

Aspects of the construction process are also covered at this time, as these can improve the score considerably. Examples are:
• responsible sourcing of materials
• Considerate Constructors Scheme
• site energy and water consumption targets
• construction site waste management

2. Design-Stage Assessment
Once the specification and drawings including the agreed design features have been prepared, the Design-Stage Assessment (DSA) can begin. This stage of the process entails gathering all the documentary design-stage evidence required by the Code, and submitting a summary of it to the Code Service Provider for certification. When the submission has passed their quality assurance (QA) processes, they issue the Interim Certificate.

3. Post-Construction Assessment
The post-construction stage assessment (PCSA) examines whether the design and construction decisions recorded in the design-stage assessment are being implemented. If there are departures from the specifications, re-assessment may be necessary, which may affect the final score and rating.
Different types of evidence are acceptable, depending on the issue being assessed — e.g. certificates, test results, written confirmation from the developer. The Assessor will use a comprehensive checklist or table of evidence to track progress. However it may be of benefit for the Client and Assessor to have regular updates to keep on top of the evidence requirements and to ensure the build proceeds according to the agreed Code formula. To support the PCSA the Assessor is expected to conduct at least one site visit.

When the home is completed the assessor submits to the Code Service Provider a summary of the evidence gathered. On passing their QA processes the Code Service provider issues the Final Certificate.

Fast-Track Process

If construction has started, or is about to start, a different process is required. Generally, beginning the assessment at this stage in a project will result in a lower score as a number of opportunities for earning credits will have been missed. In this situation the assessment process can minimise lost credits by dealing first with those issues where changes may still be possible and credits as a result clawed back, or where it may not be practicable to obtain the evidence if there is any further delay.

The next stage in the process is to obtain the required evidence relating to those issues where it is too late for any design changes. The last items to deal with are the fixed issues, generally site-related, where the evidence can be collected at any time.

Design-Stage and Post-Construction Stage Assessments follow much the same pattern as with the Preferred Process, although they may take place concurrently with Pre-Assessment.

Conclusion

The Code, with its measurement of environmental impact, is accelerating the construction of sustainable housing.

A Code score is determined by site selection, design and construction matters but can also be influenced by the assessment process itself, in that some credits can be lost if the respective issues are assessed late. For this reason, the sequence of attack is important, although this sequence is generally the same for all projects.

Starting the assessment process early is likely to result in higher scores and lower costs. For a variety of reasons, however, some assessments do start late, and in this situation the assessment process must be driven by the particular priorities of the project at the time with the aim of minimising both lost credits and additional costs.

 

Copyright © Eco-Rating Services Ltd | 2010-11

Home| Code | Code detail | EcoHomes | EcoHomes Detail | Our Customers | Glossary | Contact Us