Last edited 06 Dec 2018

Main author

Tom Blois-Brooke Engineer Website

BREEAM Testing and inspecting building fabric

Contents

[edit] Background

The requirements for air tightness testing and thermographic surveys stem from criterion 4 of Approved Document L2A – Conservation of Fuel and Power in New Buildings other than Dwellings. Criterion 4 falls under Section 3 which looks at the Quality of Construction and Commissioning, a key element of which is the building fabric.

The Approved Document states the following with regards to building fabric performance:

3.2 The building fabric should be constructed to a reasonable quality so that:

a. the insulation is reasonably continuous over the whole building envelope; and

b. the air permeability is within reasonable limits.

Compliance with the above can be demonstrated as follows:

Continuity of Insulation:

Air Permeability and Pressure Testing:

  • Pressure testing should be undertaken in accordance with the approved procedure as set out in the ATTMA publication Measuring Air Permeability of Building Envelopes.
  • All buildings that are not dwellings must be subject to pressure testing, although there are some exceptions as set out in section 3.12 of the Approved Document.
  • One listed exception which an assessor may come across more often relates to large complex buildings where, due to the building size or complexity, it may be impractical to carry out pressure testing of the whole building. The ATTMA publication indicates situations where such considerations might apply. If this approach is adopted, a detailed justification should be provided and endorsed by a suitably qualified professional (such as a competent person approved for pressure testing). The suitably qualified professional should be appointed to undertake a detailed programme of design development, component testing and site supervision to give confidence that a continuous air barrier will be achieved.
  • The measured air permeability should not be worse than the limiting value of 10 m3/(hm2) at 50Pa.
  • Should satisfactory performance not be achieved, remedial measures should be carried out on the building and new tests carried out until the building achieves the design criteria.

BREEAM and Airtightness Testing / Thermographic Surveys

The requirements of this issue, as is common with BREEAM, go above and beyond the standard requirements to promote best practice through the industry through the use of airtightness testing (as set out in the Approved Document) and also thermographic surveys to quality-assure the integrity of the building fabric. This includes continuity of insulation, avoidance of thermal bridging and air leakage paths.

The credit also requires the Main Contractor to rectify any defects identified in the thermographic survey prior to building handover.

[edit] Aim and benefits

BRE Report 176 (A Practical Guide to Infra-Red Thermography for Building Surveys) states that thermographic surveys can be used to demonstrate performance of a building and its components and services including:

  1. Insulation defect detection
  2. Air leakage detection
  3. Heat loss through window frames
  4. Dampness detection
  5. Examination of heating systems (e.g. damage to insulation)
  6. Preventative maintenance
  7. Electrical defect detection

Many of the above are not applicable to the BREEAM scope so the key benefits are stated below:

  • A thermographic survey is the best non-destructive testing method and large areas can be surveyed in a short period of time and typically alongside the air-tightness test which will quantify the leaks identified on an air tightness test.

[edit] When to consider

  • Strict weather conditions make it advisable to not carry out surveys between mid-June – mid September. The reason for this is that Internal / external temperature difference on the entire building must be a minimum of 10°C for at least 12 hours prior to the survey. If not, you will not achieve compliance for BREEAM credit or BS EN 13187:1999

[edit] Step by step guidance

There are two approaches that can be adopted for carrying out thermographic inspections:

  • Qualitative Approach: a straightforward approach that can be used to identify items such as missing or defective insulation without the need for measurement detail. The images generated from this type of survey require interpretation by a skilled operator through examination of the thermographic images and the building structure.
  • Quantitative Approach: a more detailed and stringent survey that requires analysis by a software package and produces a more comprehensive analysis of the building performance.

The operator will use their expertise to assess the survey data to identify any defective areas that require remediation, based on the building construction methods and specified design criteria.

The BREEAM criteria are not prescriptive on the approach that should be adopted and advice should be sought from the project team on which is appropriate given the nature and complexity of the building being assessed. The wording of the criteria suggests that a qualitative assessment would be sufficient to meet the credit requirements but there are benefits in undertaking a quantitative approach for more complex buildings that may justify the increased expenditure. It should be noted that, having completed a qualitative level survey, if a decision is subsequently made to follow the quantitative approach it is likely that the surveys would need to be redone as the level of detail required is increased.

[edit] Questions to ask while seeking compliance

Awaiting content

[edit] Tools and resources

UK Thermography Association: http://www.bindt.org/institute-committees-and-groups/institute-groups/ukta/

[edit] Tips and best practice

[edit] Typical evidence

A survey report from a Level 2 Thermographer in accordance with all necessary standards and current regulations

[edit] Applicable Schemes

The guidelines collated in this ISD aim to support sustainable best practice in the topic described. This issue may apply in multiple BREEAM schemes covering different stages in the life of a building, different building types and different year versions. Some content may be generic but scheme nuances should also be taken into account. Refer to the comments below and related articles to this one to understand these nuances. See this document for further guidelines.


BRE Global does not endorse any of the content posted and use of the content will not guarantee the meeting of certification criteria.

Authors:

- Tom Blois-Brooke

- Dan Widdon-

- Yasmin Spain

--Tom Blois-Brooke 09:20, 04 Dec 2018 (BST)