BREEAM FAQs

BREEAM stands for Building Research Establishment Environmental Assessment.
BREEAM is an environmental assessment method for buildings and large scale developments. It sets the standard for best practice in sustainable design. BREEAM was initially established in 1990 and since then it has been regularly reviewed and updated. Revisions have been produced to coincide with updates to Part L UK Building Regulations.
BREEAM can be used to assess any UK building type. To try and make BREEAM clear, standard schemes have been developed for many building types, such as schools, offices, industrial buildings, retail developments and others.

BREEAM in the UK is slightly different to some other countries. In the UK, BREEAM has some standard schemes that have been tailored with input from key stakeholders/clients, some examples of these are healthcare, prisons and education. It is also worth knowing that if needed, bespoke criteria can be used to assess building types that do not fall into the scope of the standard schemes available. Please talk to the HRS BREEAM Team for more information on this.

For projects that cannot be assessed using the standard BREEAM schemes, BREEAM Bespoke should be used.
The green guide to specification is a reference website providing guidance for design teams, architects and BREEAM assessors on the environmental impacts for different building element specifications. Each construction build up is given a rating between A+ and E. These ratings are then used to work out the number of credits that can be awarded for some of the issues in the material section.
It is recommended that a BREEAM Assessor is appointed at the early design stage. By involving HRS in the BREEAM Assessment at this stage, it will make it easier for you to obtain the desired rating cost effectively.
It is possible to achieve a BREEAM rating however will be more difficult and costly as some early credits are likely to have been missed.
Yes, there are some credits which require action at RIBA stage 1 and 2. This is why we recommend appointing an assessor as early as possible. Please contact the HRS BREEAM Team to discuss this.
There is no set timeframe to complete a BREEAM Assessment; it will vary from project to project. The main factor will be the time taken for the design team to submit all evidence to the BREEAM assessor.
• Pass- 30%
• Good- 45%
• Very Good-55%
• Excellent -70%
• Outstanding-85%
• Good- top 50% UK new buildings
• Very Good- top 25% of new buildings
• Excellent- top 10% of new buildings
• Outstanding- top 1% of new buildings
• NHS new build Excellent
• NHS refurbishment Very Good
• Schools – Very Good >£2m
• DoE – Excellent – new build
• London Plan – Excellent/Very Good
• Clients – M&S/John Lewis – Excellent
The BREEAM UK New Construction 2014 scheme launched on 27 May 2014 and the BREEAM UK New Construction 2011 scheme closed for registrations on 30 June 2014 (with the exception of projects in Scotland).
If the building is to be assessed under 2010 Building Regulations BREEAM 2011 can be used. Satisfactory evidence will need to be provided that confirms the Building Control Officer’s requirement for compliance with an earlier version of the Building Regulations. Evidence of Building Control Officer requirements in the form of a formal written letter or email correspondence identifying the site and the relevant building control organisation, must be supplied upon registration of the building with BRE.

In addition to the above, BRE will continue to accept contractual evidence stipulating a BREEAM requirement for registration against previous BREEAM version assessments.

No, the 2008 scheme has now been closed for new registrations
The BREEAM UK Non Domestic Refurbishment and Fit Out 2014 scheme is now live.
BRE average QA check is 4 weeks but once the assessment is submitted BRE will provide you with an estimated feedback date. There is a ‘fast track’ service where BRE will QA check an assessment in 3 days, there is an extra charge of £550+vat for this.

BREEAM Simple Buildings FAQs

• Simple building defined as one where the building services and their relationship to the building fabric are ‘simple’ • Building with ‘domestic type’ arrangement • Small office, retail unit, community building, single classroom extension • One of building types listed in scope of BREEAM 2011/2014-not a mix
BRE consultation with industry, goverment and other stakeholders identified the need for a cost effective and easier method for assessing simple buildings
  • Simple heating & hot water systems i.e. gas boiler, point of use water
  • Natural ventilation
  • Domestic scale sanitary, kitchen & laundry facilities
  • Simple systems-limited commissioning
BRE QA fees for Simple Buildings will be £915; this is less expensive than buildings that are no assessed under the Simple Buildings scheme.
  • BREEAM Accredited Professional (AP)
  • Building User guide
  • Daylighting calculations
  • Indoor Air Quality (IAQ) plans
  • Indoor Air Quality (IAQ) testing
  • Thermal comfort modelling
  • Acoustic design and testing
  • SBEM and SAP
  • Low Zero Carbon (LZC) feasibility study

Indoor Air Quality FAQs

Under BREEAM 2014 Hea 02, HRS can undertake an Indoor Air Quality Plan (IAQP) and Indoor Air Quality Testing; you can achieve two BREEAM credits. It is an easy, low cost way to achieve two BREEAM credits.
Yes under BREEAM 2014 Hea 02 you can now get two BREEAM credits, one credit for having an Indoor Air Quality Plan (IAQP) prepared and one credit for carrying out the Indoor Air Quality Testing.
No, under BREEAM 2011 it is one credit for doing both.
One credit, you need to do both an Indoor Air Quality Plan (IAQP) and carry out the Indoor Air Quality Testing to be able to get the one credit.
Yes under BREEAM 2014 Hea 02 even if you fail the Indoor Air Quality Test, you can still get a credit for having HRS’ plan.
Yes HRS have highly trained staff that can put together an Indoor Air Quality Plan (IAQP) for you and also carry out the Indoor Air Quality Testing.
IAQP stands for Indoor Air Quality Plan.
The reason and aim of the BREEAM 2011 Hea 02 Credits (Indoor Air Quality) is to recognise and encourage a healthy internal environment through the specification and installation of appropriate ventilation, equipment and finishes.
The test is carried out post-construction but pre-occupancy and involves looking for the presence of volatile organic compounds, formaldehyde, moulds etc.
The percentage credit weighting for BREEAM Hea 02 is approximately 1% which makes this a simple and attractive BREEAM claim.
Prior to testing, your project will need to be at or near completion with your HVAC system fully operational for a building purge.

It is also worth noting that where levels of detected VOCs/formaldehyde/moulds are found to exceed the prescribed limits, the project team will need to confirm the measures that have or will be undertaken in accordance with the IAQ Plan to reduce the levels so that they fall within the limits.

Thermographic Surveys FAQs

A thermal image makes it easy to identify areas of missing, misplaced or discontinuous insulation. It can also be used to identify air leakage paths if used correctly. Cold air leaking into a building will cause cold patches on the surrounding fabric, which can be identified from thermal images.
No, but they provide a qualitative appreciation of the thermal properties of a building envelope, quickly, and over large areas, and the results are displayed graphically in colour. Spot temperatures are also measured which can allow for later analysis of the thermal performance of building envelopes.
A sound knowledge of construction technology (U values, emissivity of materials) allied with experience of on-site defects is required to identify the true cause of faults identified on site. Particular care needs to be taken with regard to the emissivity and reflectivity of surfaces. Surfaces with low emissivity (e.g. polished steel), appear colder than their surroundings but are sensitive to reflective heat from background sources e.g. equipment, lights, people, etc
Terminology
Air tightness / air permeability / air leakage –
defined as the resistance of the building envelope to inward or outward air permeation. Air leakage is driven by pressure differentials between inside and outside a building caused by the wind, stack effect and mechanical ventilation systems.

Air barrier or air seal line – the physical components that make up the airtight envelope of the building. The air barrier needs to be continuous around the whole envelope – roof, walls and ground floors – and needs to be durable and maintainable in the long term. The air seal line can be drawn on construction drawings.

Air tightness test or air leakage pressure test – the building is pressure tested by connecting a fan and measuring the airflow rates required to keep the building at various positive pressures.

Air permeability – expressed as the amount of air leakage in cubic metres, per hour, per square metre of envelope at a nominal pressure differential of 50 Pascals, between inside and outside the building envelope.

Q50 – air flow rate required to pressurise the building envelope to 50 Pascals, the measured unit of which is cubic metres per second.

Code for Sustainable Homes FAQs

The Code for Sustainable Homes was launched on 13th December 2006.
In March 2015 the government withdrew the code, aside from the management of legacy cases.
Ideally you need to have the assessment carried out before any construction work commences on site, in case any alterations to the design are required.
The first stage is at design stage when a dwelling is assessed. The same dwelling is then reassessed at a post construction review.
No. Only a licensed assessor can carry out and certify a property for Code for Sustainable Homes.
Code for Sustainable Homes uses 9 categories to assess dwellings. Some of the 9 categories are mandatory criteria (*denotes mandatory criteria):

  • Energy and CO2 emissions*
  • Water *
  • Materials *
  • Surface Water Run Off *
  • Waste *
  • Pollution
  • Health and Well Being (* only if wanting to obtain level 6)
  • Management
  • Ecology

Depending on the scores you achieve on each of the categories, the dwelling will attain one of six levels.

Mandatory minimum performance standards are set for some Code issues. There are three un-credited issues where the mandatory Code levels must be met to achieve a Code rating. These are:

  • Environmental impact of materials
  • Management of surface water run-off
  • Storage of non-recyclable waste and recyclable household waste

There are four further issues with minimum standards where credits can be awarded:

  • Dwelling emissions rate-credits awarded on a sliding scale where there is an improvement in the DER over Building Regulations
  • Indoor water use-credits awarded based on the reduction of potable water in the home from all sources.
  • Fabric energy efficiency- credits awarded on a sliding scale based on the building s Fabric Energy Efficiency, taken from the SAP calculations. To achieve Code Level 5 at last 7 credits must be achieved here
  • Lifetime Homes- to achieve Code Level 6 four credits under this issue must be achieved.
  • Daylighting calculations
  • Acoustic design and testing
  • SAP calculations
The Home Quality Mark is the BRE’s new voluntary standard which should become operational in October 2015. Fully trained assessors will score aspects of a new home to give an overall quality raring.

Acoustics FAQs

It is important to be clear as to the precise acoustic compliance criteria for your project, both when designing as well as assessing performance at pre-completion stage. The acoustic requirements for the building design and the manner in which acoustic performance is demonstrated always depends on the type of scheme being considered.

Below is a list of typically-applied standards:

  • Residential developments: Approved Document E, Code for Sustainable Homes, Technical Handbook Section 5 (Scotland)
  • Education: BB93 2015, APS PSBP
  • Healthcare: HTM 08-01, SHTM 08-01 (Scotland)
  • Offices: BS8233:2014, British Council for Offices Guides

In addition to the documents listed above, there may also be BREEAM 2011 / 2014 credits available, and client-specific requirements or acoustic related planning conditions applicable to the project.

For new build residential developments, or those formed by material change of use, pre-completion sound insulation testing is mandatory to demonstrate compliance with Approved Document E, unless the scheme is registered with Robust Details. For education, healthcare and office developments, testing may not be mandatory; however, it is likely that testing is a contractual requirement, particularly where the project is BREEAM registered.
Typically, acoustic testing could include the following:

  • Measurements of sound insulation, e.g. between dwellings or between classrooms – for both airborne and impact noise transmission.
  • Indoor ambient noise level measurement, over short and long-term periods.
  • Measurements of building services noise – both internally and externally.
  • Measurement of reverberation time.
Sound insulation testing is an assessment of the amount of noise reduction and between adjacent dwellings / classrooms / hotel rooms etc. There are two types of test which can be carried out, those which measure the transmission of airborne noise and those which measure the transmission of impact noise – noise generated by footfall on a floor, for example.

Airborne sound insulation testing involves placing a loudspeaker on one side of the separating wall or floor and measuring the sound level in the room the other side of the separating wall or floor to determine the level of noise reduction. Impact sound insulation testing involves placing a standardised tapping machine onto the floor of the source (upper) room and measuring the sound level in the room below.

This involves generating short bursts of sound, either from a loudspeaker, or, less-commonly these days, by popping a balloon, and then measuring the time taken for the sound level to decay by a specified amount. This gives an indication of the amount of sound being reflected by room surfaces, which generally affects the intelligibility of communication within spaces.
For residential developments, testing is normally undertaken when properties are finished but unfurnished. This normally equates to all windows and doors fitted and sealed, all sockets fitted, ceilings installed etc. It may be necessary to carry out impact testing before carpets are fitted.

For other developments, it is generally acceptable to undertake testing when the scheme is finished and fit for occupation.

In both instances, it is generally advisable to undertake testing at a preliminary stage on a small sample. This sometimes has the benefit of highlighting issues at an early enough stage for them to be rectified.

This depends on the type of testing being carried out. For sound insulation testing, 240V power within the rooms to be tested is preferable for accuracy of testing, although 110V power can also be used. Due to the high noise levels generated during sound insulation testing, no other site personnel should be allowed to access the rooms in which the testing is taking place. Any particularly noisy site activities may need to be suspended for the duration of testing.

For internal ambient noise monitoring or mechanical services noise measurements, all site activities may need to be stopped for the duration of the measurements so that the accuracy of the measurements is not compromised. Since noise associated with the construction will not be present when the scheme is occupied, its presence can negatively affect measurements.

If you’re unsure, contact HRS to discuss the requirements.

DnT,w is an measured parameter of on-site sound insulation performance. It is the actual level of sound insulation achieved between two adjacent spaces, usually taking into account sound travelling through a separating partition and through other paths with which the partition may share an interface, such as an external or corridor wall.

Rw describes the sound transmitted through a single element, such as a wall, door or window. It is measured in a laboratory

The DnT,w of a separating wall or floor will typically be around 5 to 7 dB lower than the specified Rw for the single element, due to ‘flanking’ sound transmission around the element, although it can be lower depending upon factors such as room geometry and workmanship.

When a noisy activity, such an industrial or commercial development, is introduced into a noise sensitive area, it will often be necessary to carry out a noise impact assessment, e.g. for BREEAM credits or for compliance with a planning condition.

A noise impact assessment is most commonly required for noise from mechanical services equipment, such as condensers, chillers and air handling unit. BS4142:2014 is typically used to assess whether noise from such sources is likely to give rise to complaints from people residing in nearby noise sensitive premises, e.g. dwellings, schools, hospitals, etc.

The assessment process first requires that the existing background noise levels outside the nearby noise sensitive properties be established. By using data provided by manufacturers the noise level due to the new plant items outside the noise sensitive properties is calculated and compared to the existing background noise levels to determine the likelihood of complaints. It may be necessary to take measurements of the new plant items once they become operational to confirm noise levels.

Noise impact assessments may also be required, for example, for delivery noise associated with a new retail development, or noise resulting from a new entertainment venue.

Thermal bridging and condensation analysis FAQs

Building fabric heat loss is calculated and taken into account in Part L Building regulations using the U-values for walls/floor etc. Further heat loss also occurs at junctions such as between walls and roofs, at gutters and around openings such as windows and doors. In these areas, it is known as thermal bridges, the presence of high conductivity materials crossing the insulation lead to a higher heat flow, which is locally higher than in surrounding areas. These add to the total energy demand of the building.

A second consequence of thermal bridging is the lower internal surface temperatures caused by the increased heat flow. Depending on the environmental conditions within the building and the nature of the internal surfaces this can lead to a risk of surface condensation.

Thermal bridging analysis uses 2D or 3D computer simulation depending on the nature of the detail in question to quantify the heat loss through thermal conductivity at junctions of building components.

Thermal bridging analysis can confirm thermal bridging (psi) values. These can be entered into the SBEM and SAP compliance calculations required for Part L Building Regulations to determine an overall y-value. Results can assist with carbon emissions and fabric energy efficiency targets.

Modelling can also be utilised to determine whether proposed design details pose a risk of surface condensation by calculating the temperature factor.

Information to be provided by the client to HRS will include the following:

  • Relevant drawing details by Architect /Contractor
  • Most up to date architect’s/structural details
  • Thermal conductivities for various elements contained within the details
  • Proposed building usage (main activity) and expected internal design temperatures if different from the typical known standards
HRS has experience of carrying out assessments on a full range of building types and project sizes. HRS also uses approved industry standard (ISO 10211) HEAT software coupled with trained and experienced modellers. This means that we are fully competent and qualified to provide compliant reports for client and local authority requirements.

HRS’s wide ranging technical and practical experience of building technology, design issues and potential faults in buildings allow us to give a high level of service during the modelling, interpreting the results and providing pragmatic solutions.

Daylighting Calculations FAQs

A daylighting study can be carried out to assess the levels of natural daylighting within internal building spaces.
Daylighting studies offer credits within the Code for Sustainable Homes, if modelling is carried out to confirm the following:

  • Kitchens must achieve a minimum Average Daylight Factor of at least 2%
  • All living rooms, dining rooms and studies (including any room designated as a home office under Ene 9 – Home Office) must achieve a minimum Average Daylight Factor of at least 1.5%
  • 80% of the working plane in each kitchen, living room, dining room and study (including any room designated as a home office under Ene 9 – Home Office) must receive direct light from the sky

Daylighting studies offer credits within BREEAM, if modelling is carried out to confirm the following:

  • Average daylight factors are achieved in line with the requirements for the specific building type
  • Uniformity ratio is achieved in line with the requirements for the specific building type OR
  • A view of sky from desk height (0.7m) is achieved and
  • The room depth criterion d/w +d/HW < 2/(1-RB) is satisfied.
Information to be provided by the client to HRS will include the following:

  • Building geometry data by Architect /Contractor
  • Most up to date architect’s (plans, elevations, section, and details), preferably the latest construction drawings.
  • Site plans showing adjacent buildings positions and heights
  • Solar properties for the glazing, which is total light transmittance;
  • The reflectance of the various materials finishes

In the absence of the clients specific design data, we can assume the common know values with a view to confirm these later on.

HRS has over 8 years’ experience of carrying out assessments on a full range of building types and project sizes. HRS also uses powerful IES-VE DSM software to optimise the opportunity for buildings to achieve compliance. This means that we are fully competent and qualified to provide compliant reports for client and local authority requirements.

HRS’s wide ranging technical and practical experience of building technology, design issues and potential faults in buildings allow us to give a high level of service during the modelling, interpreting the results and providing pragmatic solutions.

SAP FAQs

SAP stands for Standard Assessment Procedure.
A SAP is the Government’s approved procedure for energy rating domestic dwellings.

It is the methodology used by the Department of Energy & Climate Change (DECC) to assess and compare the energy and environmental performance of dwellings. The reason for doing this is to provide accurate and reliable assessments of dwelling energy performances that are required to underpin energy and environmental policy initiatives.

SAP works by assessing how much energy a dwelling will consume and how much carbon dioxide (CO2) will be emitted in delivering a defined level of comfort and service provision, based on standardised occupancy conditions. This enables a like-for-like comparison of dwelling performance.

Properties are awarded a rating between 1 and 100. A rating of 1 represents very high running costs, whilst a score of 100 indicates zero energy cost. It is however worth knowing that dwellings can exceed 100 where they are net exporters of energy e.g. through PV electricity generation.

A SAP is required when new dwellings are constructed and existing homes are converted or extended under current Building Regulations.
The sooner the better – DER/TER calculations must be submitted to building control before work starts on site. Earl involvement allows the energy efficiency of the dwelling to be considered whilst it is being designed, ensuring a cost effective solution to compliance is achieved.

An ‘As Built’ calculation will then be required at the end of the project before handover. It is important to consider the impact of any design changes made during construction. Apparent cost savings made during VE, may adversely affect the targeted rating for Building Regulations and Code assessments.

SBEM FAQs

SBEM stands for Simplified Building Energy Model.
SBEM is a computer program that provides an analysis of a building’s energy consumption. SBEM estimates the monthly energy use and carbon emissions of a building. This was developed for the Department for Communities and Local Government (CLG) to partially satisfy the requirements of the Energy Performance of Buildings Directive (EPBD).
Nearly all new non-domestic buildings require an SBEM prior to construction. It is normally a requirement of Building Control at this early stage. There are some exceptions, but these are very few. If you’re not sure if your building needs an SBEM assessment, please contact the HRS Energy team who would be happy to advise.
DSM stands for Dynamic Simulation Model. This is also known as thermal modelling
If your building design is complicated or has an unusual heating, cooling or ventilation strategy, then you may need a DSM (Dynamic Simulation Model). This model can be tailored to be more reflective of a complicated design. It is worth knowing that if your building design incorporates extensive glazing, non-standard wall or roof shapes or a bespoke services strategy then there is a strong possibility that you will need a DSM (Dynamic Simulation Model). If you are unsure, please contact the HRS Energy team who would be more than happy to help.


Energy Performance Certificate (EPC) FAQs

EPC stands for Energy Performance Certificate.
If you are building, planning to rent out or planning to sell a dwelling or non-dwelling, then you need to have an EPC.

Exemptions apply for:

  • Buildings used as places of worship or for religious activities
  • Temporary buildings
  • Buildings with low energy demand
  • Stand-alone buildings with a floor area <50m2
  • Buildings that are due to be demolished (certain stipulations apply)
  • Buildings and monuments officially protected as part of a designated environment, or because of their special architectural or historic merit.
An EPC is valid for ten years.
When a dwelling or non-dwelling is being offered for sale, the seller must make an EPC available to prospective buyers. If it is in the process of being offered to let, the prospective landlord must make an EPC available.
Please contact HRS on 0800 030 4391 or e-mail info@hrsservices.co.uk and one of HRS’s highly experienced Energy Assessors would be more than happy to discuss your requirements.
As an EPC outlines the energy efficiency of a dwelling or non-dwelling. The HRS Energy Assessor would request all relevant information. This would include architectural drawings information and details of services to be installed. All this information is then analysed by one of HRS’s Energy Assessors and an EPC is produced.
An EPC provides you and the new owners with an energy efficiency rating for the dwelling or non-dwelling. These are expressed in a rating between ‘A+’ and ‘G’ (A+ being the most efficient). The EPC also contains information on the potential savings that could be made, through the provision of a recommendations report. This includes actions that are not mandatory, but could be used to further enhance the performance of the building, if adhered to.
Prices depend on the number, size and complexity complexity of dwellings or non-dwellings. Please contact HRS on 0800 030 4391 or e-mail info@hrsservices.co.uk and one of HRS’s highly experienced Energy Assessors would be more than happy to discuss your requirements.

Display Energy Certificates (DEC) FAQs

DEC stands for Display Energy Certificate.
If the building is greater than 250m2 and is occupied or part-occupied by a public authority or institution, or if the building will provide a public service that is visited by the public, then your building may need to have a DEC.
It is the responsibility of the public authority or relevant institution providing a public service to display a DEC in each of their buildings affected by the legislation.
Please contact HRS on 0800 030 4391 or e-mail info@hrsservices.co.uk and one of HRS’s highly experienced Energy Assessors would be more than happy to discuss your requirements.
For a Display Energy Certificate, energy consumption information is assessed. The gross internal area of the building, as well as its type of operation, are both taken into account. Please note that actual meter readings or consignment notes for all fossil fuels used in your buildings are required under this legislation.
A DEC is a chart showing a building’s operational rating, carbon dioxide emissions and previous operational ratings for the last three years. The operational rating measures the energy efficiency of a building on a scale of ‘A’ to ‘G’, where ‘A’ is the most efficient. HRS will also provide you with an advisory report. This is provided to you at the same time that you get your DEC. This report will contain recommendations on ways in which the energy efficiency of the building can be improved.
Yes. Where the building has a total useful floor area of more than 1,000m², a Display Energy Certificate is only valid for 12 months. The accompanying advisory report is valid for seven years. Display Energy Certificates and advisory reports for smaller buildings are valid for 10 years.
The cost will vary depending on the size and type of the building which requires a DEC. Please contact HRS on 0800 030 4391 or e-mail info@hrsservices.co.uk and one of HRS’s highly experienced Energy Assessors would be more than happy to discuss your requirements.

Air Sealing FAQs

Careful consideration is needed on all structural elements. For instance, pre-cast concrete floors may look airtight, but consider air leakage along open voids through the slab into cavities in external walls. Also think about non-structural elements such as roof liner sheets or T and G boarding. A 1mm gap along each joint adds up to a considerable area for air to leak through.
Reaching the worst acceptable air permeability rate of 10m3/(h.m2) set down in Part L is achievable by air sealing the obvious leakage paths reasonably well. To reach the current best practice for buildings of 2m3/(h.m2) is more than 5 times the air sealing works. Attention to detail and a systematic, very high standard of work must be attained across the whole site.
Additional building costs may amount to 0.5%. This ignores cost savings from downsizing heating plant and the lifetime reduction in energy costs.
The robustness of materials and air sealing details need to be carefully considered, in order that the air sealing works will last the life span of the building. Great care should be taken when the finishes of the building or vapour control layers are used. Plasterboard and vapour control layers can be easily damaged, leading to high levels of air leakage.
A detailed understanding of all the requirements is necessary in order to build up a comprehensive specification that will work well on site. Addressing 2 out of the 3 issues (air/fire/acoustics) can prove to be a real problem.
Dry lining – there may be expansion joints etc behind the lining boards that do not get properly sealed as they are not going to be on display. Additionally if the blockwork used has a high porosity, then using the dry lining will reduce the problem caused by air leakage through the blockwork.

Ensure any exposed edges including where the lining boards finish below raised access floors and penetrations to dry lining are sealed.

Care will need to be paid to any areas of exposed blockwork above suspended ceilings, below floors and behind demountable panels etc that any joints, junctions and penetrations are sealed with air tight materials.

Yes, if not porous – rigid and foil faced boards and pasted batt systems are suitable provided board joints, junctions etc are sealed.

Loose mineral wool is not suitable. Any compressed mineral wool system used say to wall heads should be overcoated with either intumescent or ablative paste for air tightness.

Use the same principles of design and construction as for other air tightness works but use fire rated materials. Compliance to various sections of Part L1 and L2 can be achieved by a ‘competent person’ reviewing the design and/or site works and deeming them adequate. These sections include air tightness and continuity of insulation for all buildings. HRS can take on this role and issue the necessary declaration to the Building Control Officer.
A detailed understanding of all the requirements is necessary in order to build up a comprehensive specification that will work well on site. Addressing 2 out of the 3 issues (air/fire/acoustics) can prove to be a real problem.
Services can be routed through ducts inside the building envelope. Sealing multiple service penetrations is awkward but similar principles to those used to seal penetrations through fire walls and plant room slabs should be used.
For plenums to be effective, they need to be reasonably air tight. HRS have air sealed and tested a variety of plenums and can offer advice for any particular project.
Block Work
In terms of workmanship, all bed and vertical mortar joints between blocks should be fully filled and not ‘faced up’. All block to steel junctions at columns, wind posts, floor beams, horizontal channels etc should be filled. Any expansion joints should be sealed with a sealant on a backer rod.

Some 7N blocks can leak up to 140m3/hour/m2 at 50 Pascals!!

Fair face / paint grade block work usually exhibits an air leakage rate of 5–10m3/(h.m2) at 50 Pascals.

Solid ROOF LINER SHEET AS part of a built up roof system
Liner tray – the inner liner tray will form an excellent air seal if all lap joints and penetrations through the liner tray are air sealed. The inside of the liner tray should be taken as the air seal line, with all penetrations through it being directly sealed into it, preventing air leakage into the roof void. All lap joints should be air sealed using an appropriate sealant tape and any open profiles filled with closed cell foam fillers. All junctions between wall liner trays and other wall elements / cladding can be sealed using pressed metal flashing trays, EDPMs or similar to bridge gaps.

The Metal Cladding and Roofing Manufacturers Association MCRMA have a Technical Guideline Number 14 setting out design details for profile roof cladding, which is a very useful design reference document.

Curtain Walling
Curtain walling if built to a ‘good’ CWCT standard will leak at <0.5m3/(h.m2) at 50 Pascals. Curtain walling should be air sealed to the adjacent air sealed wall element with an EPDM detail or similar. Careful on site quality control is required on site to ensure the EDPM is installed and dressed correctly to adjacent air sealed elements.

Composite Panels

Composite profiled and trapezoidal panels should be constructed to robust air sealing details as supplied by Wards, Kingspan and the like. If so, they should leak at <5m3/(h.m2) at 50 Pascals, if built to a reasonable standard.

Plasterboard / Dry Lining
To minimise the quantity of potential air leakage paths past plasterboard on external walls, the plasterboard should ideally be as complete as possible with a minimum number of penetrations through it.

The heads and bases of all plasterboard should be sealed to the floor slab, along the full perimeter length.

Careful detailing is required for all plasterboard along the external wall including junctions with internal partitions; service penetrations; dado rails; light fittings etc.

If you have any queries regarding the specification or detailing for materials/components to be used, please contact HRS for further advice.

Air Tightness FAQs

Air tightness is also sometimes referred to as ‘air leakage’ or ‘air permeability’ – they all refer to the same thing. They all describe the infiltration of cold or hot air into a building and the loss of heated/cooled air from inside the building through gaps, cracks, holes, etc in the building fabric.

The loss or cooling/heating of this ‘conditioned air’ through ‘uncontrolled ventilation’ affects the energy consumption of the building, as additional energy will be required to re-heat or re-cool the air. It also impacts on the comfort levels of the people that are working / living / shopping etc in the building.
Yes it is, but many clients do specify a lower air tightness target so it is strongly advised that you always check at the start of your project what air tightness target you are working to.
Part L1 applies to dwellings and Part L2 to non-domestic buildings.
Part L1A and L2A refer to new buildings and Part L1B and L2B to refurbishments.
  • ATTMA TSL1 Measuring Air Permeability of Dwellings
  • ATTMA TSL2 Measuring Air Permeability of Non Dwellings
  • BS EN 13829:2001 Thermal Performance of Buildings: Determination of air permeability of buildings – Fan pressurisation method
The envelope area is the total internal surface area of the conditioned areas of the building, i.e. the sum of the floor area, wall areas and ceiling area (of the heated space).
The table below from ATTMA TS1 states the best practice and normal air tightness criteria for different building types:

Type

Air permeability m3/(h.m2) at 50 Pa

Best Practice Normal Max Part L Requirement
Offices 10
Naturally ventilated 3 7
Mixed mode 2.5 5
Air conditioned / low energy 2 5
Factories/ warehouses  2  6
Superstores 1 5
Schools 3 9
Hospitals 5 9
Museums & archival stores  1  1.5
Cold stores 0.2 0.35
Dweillings
Nautrally ventilated 3 9
  • Part L 2010 specifies that the air seal line is to be contiguous with the warm side of the insulation
  • The air test must encapsulate the thermal envelope of building, so identify any excluded areas such as un-heated plant rooms
  • Identify both the primary air seal line and the secondary air seal line which will minimise the risk of failure
  • The primary air seal line is based on the technically correct element being air sealed in terms of both the technical and Part L requirements
  • The secondary air seal line is adopted as a back up to the primary air seal and reduces the risk of the air test failing and can be viewed as the contractors friend. It should never be solely relied on
  • Consider continuity of insulation, thermal bridging, vapour control, condensation risk, fire strategy
  • Where plasterboard is used as an air seal line consider flanking sound issues
  • Build tight, ventilate right – fabric first approach
A building will fail Part L if the air permeability rate is >10m3/(h.m2). More stringent requirements may be in place, depending on the requirements within the SBEM calculation to satisfy the carbon emissions target.

Buildings could also fail if thermographic inspections of the visible envelope show that the insulation is not reasonably continuous.

A variety of techniques can be used to identify leakage paths. These include:

  • Feeling for draughts adjacent to the air barrier, whilst the building is being air leakage pressure tested.
  • It is useful if the air test fan unit can pressurise and de-pressurise buildings so that draughts can be felt for on both the internal and external faces of the air barrier.
  • Running localised smoke tests using a hand held smoke generator or smoke pens.
  • Running a smoke test on the whole building & recording results on video.
  • Carrying out a thermographic survey.
  • Physically checking over the risk areas looking for holes, gaps, etc.
Yes the air tightness of a building is very important, a building’s air tightness plays a significant role in its energy efficiency.

Here are just some of the many reasons why you should think about air tightness when designing and constructing your building:

  • Studies have shown that the built environment contributes about 50% of carbon emissions
  • Studies have shown there are links between carbon emissions and global warming
  • The comfort of the people using the building – insufficient air tightness could mean the building is too hot or too cold, which ultimately means unhappy building occupiers
Yes you can do this, however it is not advised as you may find it harder to achieve your SAP rating without doing an air test.
The accuracy of the air leakage pressure test itself will be affected by the strength and gustiness of the wind. The wind will impose both positive and negative pressures on the building envelope, which will vary during the test. ATTMA TS1 states that tests should normally only be carried out when static pressures within the building are not excessive.
Yes, as long as no-one opens a door or access hatch which forms part of the air barrier – which basically allows the pressure to drop and the test would need to be run again.
Use the same principles of design and construction as for other air tightness works but use fire rated materials. Compliance to various sections of Part L1 and L2 can be achieved by a ‘competent person’ reviewing the design and/or site works and deeming them adequate. These sections include air tightness and continuity of insulation for all buildings. HRS can take on this role and issue the necessary declaration to the Building Control Officer.
No. However, the building needs to be emptied of all people for health and safety reasons. It is also a good idea to inform the fire brigade to avoid unnecessary call outs. The smoke is a harmless food grade water based mono-propylene glycol (MPG), but it is a good idea not to expose fresh food or produce to it.
Some temporary sealing is allowed within the air tightness standard, i.e. mechanical ventilation and trickle vents can be taped. However windows and doors can not. All drainage traps need to be filled with water. If you are unsure, please contact one of the HRS Air Tightness team who would be more than happy to advise.
Robust air sealing details are often a matter of common sense – will it last 20 years? – adhesion – movement – wind load – fire rating
Generally good fire/acoustic seal = a good air seal
Poor air seal details include un-specified tapes, un-supported sheet materials such as polythene, canister/crazy foam, un-faced rockwool, and breaks in the air seal line
LOOK FOR CONTINUITY BETWEEN AIR SEALED ELEMENTS
Careful consideration is needed on all structural elements. For instance, pre-cast concrete floors may look airtight, but consider air leakage along open voids through the slab into cavities in external walls. Also think about non-structural elements such as roof liner sheets or T and G boarding. A 1mm gap along each joint adds up to a considerable area for air to leak through.
Services can be routed through ducts inside the building envelope. Sealing multiple service penetrations is awkward but similar principles to those used to seal penetrations through fire walls and plant room slabs should be used.
Components could be tested in laboratories or tested on site in specially built enclosures as specified in BS EN 12114:2000. The test method allows the air leakage through individual joints to be derived. From this information the building air leakage rate can be estimated by totaling up the leakage rates for all the joints in the building envelope.
As with all gaps and joints, there are many BS EN Standards which specify in detail how they can be bridged effectively. Materials not to use include materials permeable to air (e.g. mineral fibre) or flimsy sheets, thin gaffer tapes or similar. Sealant, expanding foam and tapes can be used, if specified and applied correctly. Ensure that all materials and components are fit for purpose and installed to current standards.
Use similar methods to those used at present to control all aspects of contracts specification, method statements, quality management systems, etc. Problems generally occur when responsibilities for each element or package of work are not clearly defined and agreed, prior to site work starting.
Apart from the obvious – unsealed blockwork, hollow concrete beams or floor planks, joints/junctions in curtain walling and dry lining systems, hollow frames/mullions/transoms, hollow steel sections penetrating the roof or walls, lap joints on roof liner sheets or T & G boarding – to name a few!
Dividing Q50 by 5.5 gives an approximate figure for the total leakage area in metres squared. For example; if Q50 = 37m3/s the total leakage area = 6.7m2. Treat this figure with respect and care as the visual hole seen on the air seal line is not always the actual area.

Passivhaus FAQs

HRS have worked on a number of Passivhaus schemes, so have extensive practical and technical experience. A Passivhaus project and an award winning building that HRS were heavily involved in is the prestigious Passivhaus Interserve Offices in Leicester.

The HRS Passivhaus air tightness consultancy service will ensure you get the right advice at the right stage to achieve the Passivhaus standard. It is crucial if you are working to the Passivhaus standard that you contact HRS early – it never to soon to contact us.

Passivhaus (or ‘Passive House’) is the fastest growing energy performance standard in the world. It is said that the Passivhaus standards strengths lie in the simplicity of its approach; build a house that has an excellent thermal performance, exceptional air tightness with mechanical ventilation.
The objective for a Passivhaus building is that thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions, without the need for additional recirculation of air.
Passivhaus is often compared and confused with the Code for Sustainable Homes and BREEAM ratings for non-domestic buildings. They are not the same: Passivhaus is a specific energy performance standard that delivers very high levels of energy efficiency, whilst the Code and BREEAM are overarching sustainability assessment ratings which address a large number of environmental issues.
No. It is a misconception that the Passivhaus standard only applies to residential dwellings. The Passivhaus standard can also be applied to commercial, industrial and public buildings.
The Passivhaus standard was developed in Germany in the early 1990s by Professors Bo Adamson of Sweden and Wolfgang Feist of Germany and the first dwellings to be completed to the Passivhaus Standard were constructed in Darmstadt in 1991.
There is often confusion over the Passivhaus standard as it can be confused with the more generic approaches to passive solar architecture, as it does shares some common principles.

Where the Passivhaus standard is not the same as the more generic concepts is in Passivhaus’s ability to reduce the permitted space heating demand and primary energy consumption. This means it can be considered as both a robust energy performance specification and a holistic low energy design concept.
Passivhaus thermal comfort is achieved to a greatest practical extent through the use of passive measures. Please see the list below – this can be applied to the residential dwellings, commercial, industrial and public buildings:

  • Good levels of insulation with minimal thermal bridges
  • Passive solar gains and internal heat sources
  • Excellent level of airtightness
  • Good indoor air quality, provided by a whole house mechanical ventilation system with highly efficient heat recovery

There are no strict requirements with respect to domestic hot water, lighting and appliance consumption. The standard imposes an overall limit on the Primary Energy consumption which promotes energy efficiency in all of these areas.

The Passivhaus standard is a comprehensive low energy standard intended primarily for new buildings.

The following energy performance targets define the standard and must be met in order for certification to be achieved.

  • Energy performance targets and air changes per hour
  • Specific Heating Demand ≤ 15 kWh/m². yr
  • Specific Cooling Demand ≤ 15 kWh/m². yr
  • Specific Heating Load ≤ 10 W/m²
  • Specific Primary Energy Demand ≤ 120 kWh/m². Yr
  • Air Changes Per Hour ≤ 0.6 @ n50

It is possible to achieve the Passivhaus standard when refurbishing buildings, although this can be a lot more costly.

The standard requires that the Primary Energy demand target is met in all cases, this figure must include the space heating, domestic hot water, lighting, fans and pumps and also all of the projected appliance consumption. In addition to the primary energy demand the standard permits that either the Specific Heating Demand or the Specific Heating Load must be met.

Yes – the energy balance of the proposed building must be verified using the Passivhaus Planning Package (PHPP) using the appropriate regional climatic dataset. Either the monthly or the annual method may be applied.

If the Specific Heat Demand is ≤ 8kWh/m².yr or the ratio of free heat gains to heat losses is greater than 0.70, it is recommended that the monthly method is used to ensure accuracy.

The standard provides limiting backstop values for the glazing specification, ventilation systems, air tightness levels and thermal bridging, as these factors should not exceed these limits in order that the thermal comfort criteria can be maintained.
The following table illustrates the elemental backstop values which should not be exceeded in order for the Passivhaus certification criteria to be met.

  • Design Component Limiting value
  • Walls, Roof, Floor (U-values)* ≤0.15 (W/m²K)
  • Glazing unit ≤0.8 (W/m²K)
  • Installed glazing ≤0.85 (W/m²K)
  • Doors ≤0.8 (W/m²K)
  • Infiltration (ach-1) ≤0.6 @ n50
  • Thermal bridging (linear ψ value) ≤0.01 (W/mK)
  • MVHR coefficient (η HR) ≥0.75
  • Ventilation electric limit 0.45 Wh/m3
  • Appliances High efficiency recommended
  • Lighting High efficiency recommended
  • On site renewables No requirement but SHW typical

* please note opaque U-values are only recommended targets and are not critical to certification.

The backstops above apply to moderate weather regions only, for warmer climates the performance values could be reduced. Please consult your building certifier for more information.

A refurbished building can be certified as a “Quality-Approved Passivhaus” if the certification criteria for Passivhaus are met when refurbishing a building – this is based on the same criteria as for new buildings. It can however be very difficult to achieve the Passivhaus standard for older buildings for various reasons.

If you are able to use Passivhaus technology for all relevant building components in your existing buildings, it will lead to substantial improvement in respect of thermal comfort, structural protection, cost-effectiveness and energy requirements.

If a building is refurbished using Passivhaus components and largely with exterior wall insulation, it can be certified to the EnerPHit standard. This will then show evidence of quality assurance and verify achievement of the specific energy values.
The designation EnerPHit+i is used if more than 25% of the opaque exterior wall surface has interior insulation. It will be likely that moisture analysis will be needed where opaque elements are insulated internally.
The standards have slightly relaxed certification criteria, as indicated below:
Criteria Passivhaus EnerPHit
Specific Heat Demand ≤ 15 kWh/m².yr ≤ 25 kWh/m².yr
Primary Energy Demand ≤ 120 kWh/m².yr ≤ 120 kWh/m².yr *
Limiting Value n50 ≤0.6-1 n50 ≤1.0-1
* PE ≤ 120 kWh/m².yr + ((SHD – 15 kWh/ m².yr) x1.2)
As with new build projects, the energy balance of the refurbished building must be verified using the Passivhaus Planning Package (PHPP). For calculation of the specific space heat demand, both the monthly as well as the annual method can be applied, see the Outline Specifications above for further details.

Plenums – FAQs

Do you have plenums in your building? If the answer is yes, you need to be aware that a staggering 70% (approximately) fail their first air test. HRS have years of experience of raised access floor plenum air pressure testing and can work with you to ensure you pass first time – the key is to contact HRS early.

HRS can ensure that a site advice visit is arranged as soon as the floor is in place, we can then assess your design and offer you specification advice to ensure that your plenums are adequately sealed.

A plenum is part of a building that normally facilitates air circulation for heating and air conditioning systems by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure. Typically this is under a raised floor or between the structural ceiling and the suspended ceiling.
70% of plenums fail their first air test as there is still a lack of understanding within the construction industry as to how airtight a plenum needs to be. Often people are working on information about plenums that have been tested in a lab under laboratory conditions, and as everyone that has worked on a construction site knows, there is a big gap between what happens in a lab to the reality of plenums on a construction site. With multiple contractors needing to put pipes, cables etc through the plenum, this is just one of many things that can affect the air tightness of a plenum. HRS have years of experience and can work with you to ensure you pass your air test first time.
HRS plenum desktop and on site design reviews assess how elements of the plenum are specified and how they are integrated together to form a workable plenum.
In brief, a tile is removed from the plenum for a celotex tunnel leading to the HRS fan.

Any air handling ducts serving the test zone need to be turned off, isolated and temporarily sealed, stopping the passage of air to outside of the test zone via ductwork. Once the area has been prepared and the fan set up, the test takes place in the same way as a HRS normal air pressure test, i.e. taking a number of pressure readings over a period of about 30 to 45 minutes.

If your test fails, your HRS air tightness technician will carry out a smoke test to look for air leakage paths and sometimes it is possible to carry out remedial works.

At present there is no set standard for plenum testing. The specification is usually set by the project’s Mechanical Engineers, and is normally set in litres per second per square metre (l/s/m2). HRS will need to know what pressure the specification is set at, e.g. 0.5l/s/m2 @ 50 Pascals. It is possible that the specification can be set in l/s/m3 and for this HRS would require the volume of the RAF Plenum.
If your plenum has failed, don’t panic! HRS have extensive experience of carrying out plenum remedial works (when we have not be contacted at an early stage, to give the help and advise that is needed).

HRS’s practical and technical expertise means we can identify defects/problem areas and carry out the necessary remedial works.

Room Integrity Testing FAQs

A room integrity test predicts how long the fire suppressant agent will remain above minimum concentration levels within the protected area of the enclosure. A retention time of 10 minutes is the minimum period specified in the British Standard, unless otherwise specified by the authority. The testing is conducted using specifically designed computer software, in compliance with BS EN 15004/ ISO 14520 Annex E Enclosure Integrity Procedure and HRS equipment calibrated to UKAS standards annually.
Yes, Room Integrity Testing is also known as Gas Suppression Testing, Enclosure Integrity Testing and Hold Time Testing, but they are all the same test.
HRS’s highly trained technicians will use smoke pencils to isolate the problem areas. If the problem area can be sealed on the day and if there is time, a second test can be carried out on the same day.
The test is requirement of the British Standard for Fixed Firefighting Systems – BS EN 15004. This must be done when a gaseous system is installed, then it should be repeated every year.
Yes, if the room is modified and there is even a slight chance that the seal could have been broken or damaged in any way, another room integrity test should be carried out.

It is worth noting that most, if not all insurance companies will require you to provide them with evidence that a second test has been carried out after modification works.

Yes, HRS have highly trained and experienced air sealing teams that can easily locate those problem areas and air seal them for you.
Any air conditioning systems would need to be in the condition they would be in the event of the gaseous fire suppression system being deployed (i.e. in the event of a fire).
Yes, on passing HRS will provide you with a full report in compliance with BS EN 15004/ISO 14520 Annex E Enclosure Integrity Procedures and using FSSA peak pressure calculations.