The AECB Building Standard (previously known as Silver standard)

What is the AECB Building Standard?

AECB Building Standard Certification

The AECB Building Standard is aimed at those wishing to create high-performance buildings using widely available technology at little or no extra cost. We estimate that this low-risk option will reduce overall CO2 emissions by 70% compared to the UK average for buildings of each type. Individual self-builders and large-scale residential and non-residential developers could make a valuable contribution to low-carbon building by meeting the AECB Building Standard.  To see examples of projects built to this standard go to the Low Energy Buildings Database.

How do I get a project designed and built to the AECB Building Standard?

Your existing project manager may have the experience necessary to create an AECB Building Standard project or you can employ a certified Passivhaus designer/consultant within your design team. Not only have they got the skills, they also have the practical knowledge about what works and what doesn’t.

Architects and Engineers
If you are about to embark upon an AECB Building Standard project and you’re already a certified Passivhaus designer/consultant then you pretty much know all you need to know. Now all you need to do is execute what you already know to the best of your ability.
If you’re not a certified Passivhaus designer/consultant and do not have the necessary experience then you may wish to become trained. You will not only learn how to use the Passivhaus Planning Package (the fundamental design tool used in AECB Building Standard projects), you will also discover how to mitigate thermal bridging and minimise air leakage.

AECB Building Standard is not without its challenges. Providing your design team has experience and a good track record then you are in a good position. If not you may consider employing an appropriately experienced person or a certified Passivhaus designer/consultant to review the design, construction details and PHPP calculations.
One of the biggest risks on large projects is the loss of knowledge and skills while you’re on site. If not managed properly this can set you back. One of the best things you can do is ensure quality, consistency and continuity of onsite labour. After a series of trade specific tool box talks it’s simply a case of being careful and diligent.

Why should I build to the AECB Building Standard?

One of the primary benefits of AECB Building Standard is choice. Working with your design team you will be able to determine the fabric standards and ventilation systems that suit your needs. This gives you the opportunity to consider how ventilation systems will be used and maintained throughout the project lifecycle without being bound to mechanical ventilation heat recovery.
At the same time, by focusing upon a fabric first methodology, you can make the most of passive and low energy design and technology. This serves to reduce energy demand and minimise lifecycle cost.

Architects and Engineers
AECB Building Standard is an ideal vehicle for conscientious professionals committed to creating sustainable low energy, low carbon buildings. If you lack the knowledge and experience you can employ a certified Passivhaus designer/consultant although this is not mandatory.

If you want to demonstrate your prowess at construction and the quality of craftsmanship of your trades, AECB Building Standard will suit you down to the ground. If you have not built a Passivhaus then AECB Building Standard provides an opportunity to stretch yourself without such an onerous airtightness target. Once you have the experience you will be able to progress on to Passivhaus with much greater confidence.

Can the AECB Building Standard only be designed and built by AECB members?

No, however the design & detailing advice to support building to the AECB and Passivhaus Standard can only be downloaded free of charge by an AECB member so one of the design team should be a member.

Not an AECB member? Join now

Applying the AECB Building Standard to a retrofit project

If you are applying the building standard to a retrofit project you may need training in delivering moisture-robust energy efficiency measures.  Read about our advanced retrofit training course which is studied online at your own convenience here.

You may wish to incorporate environmental condition monitoring into your project (especially if it is a retrofit): Read about the Omnisense remote monitoring system here.


Independent certification was considered as it could, in principal, be provided by Passivhaus certifiers. However, the AECB opted to provide a less formal option for its members and therefore a self certification route has been developed.  This means the self certifier (typically the building’s energy consultant) takes responsibility for certification and for underwriting the standard claim. The AECB has provided a form of declaration for completion by the certifying consultant but will deliberately not audit or take responsibility for the certification.

The AECB self certification process is designed to make explicit the project’s claim to be a low energy design and to provide the consumer with a degree of protection under trading standards – without the AECB having to get involved in quality control and legal matters.

This approach puts the responsibility for performance claims clearly with the person signing the certificate and a duty of care on the client to ensure that the consultant is competent and suitably insured.

AECB Building Standard certification costs

All prices are plus VAT and are for guidance only as each project will be individually assessed.

Guide prices for domestic buildings (per unit or terrace block)
Floor Area m2 AECB members Non members
up to 250m2 £50 £250
251 – 1500m2 £150 £750
1501m2 and < 3000m2 £180 £900
3001m2 and above £250 £1250

Charges for non domestic buildings will be based on the above prices, based on floor area with an additional cost of up to 50%, the final cost to be advised on application to cover the relevant complexity of the project.

How can I find consultants that can certify my project?

Many members of the AECB are experienced in low energy building.  You can search our members in our Members Directory or find a certified Passivhaus designer/consultant database of certified Passive House designers/consultants. Please note that when searching our Members Directory, we are not an accrediting body and so membership does not guarantee competence.

Download AECB design and construction guidance

AECB members only, design and construction guidance can be downloaded from here.

Not an AECB member? Join now 

AECB Building Standard criteria

The AECB Building Standard can be said to be achieved where a building that is designed and modelled using PHPP1 in accordance with current Passivhaus methodology meets the following requirements:

Parameter Target Notes
Delivered Heat and cooling ≤ 40kWh/(m².a) According to PHPP * and Passivhaus methodology.
Primary Energy demand Varies kWh/(m².a)**** ditto
Air tightness (n50) ≤ 1.5 h-1 (≤ 3 h-1) With MVHR (with MEV) **
Thermal Bridges *** Psiexternal <0.01 W/mK Calculated if > 0.01 W/mK
Summer overheating <10% <5% recommended

* Passive House Planning Package.
** it may not be possible to meet the heat demand target without MVHR for some buildings.
*** Standard Passivhaus methodology is used. If no calculation is submitted, then the decision as to whether a detail is thermal bridge free may be queried at the discretion of the AECB.
****PE demand varies by country according to each nations PE ratio. As of PHPP 9.6 UK PE is 135 kWh/(m².a)  Note: The Primary Energy requirements have changed because PHI have updated PHPP – the latest version of PHPP recognises national variations in Primary Energy factors.  If your project was started using an older version of PHPP i.e. the calculations use PHPP 9.1 or earlier, then please continue to use the same 120 kWh.m2.yr PE limit that your version of PGPP requires for ‘Classic Passivhaus’ in order to certify your project.

Thermal bridges

The AECB Building Standard uses the Passivhaus approach of using external dimensions to simplify modelling. It also requires that thermal bridges are minimised and there are the necessary guards against mould and condensation. Psi-values shall comply with Table 1.

Winter comfort requirements

Whilst the Passivhaus approach simplifies the achievement of winter comfort conditions by requiring surface temperatures including glazing to be greater than 17°C, this is unlikely to be achieved with all AECB Building Standard buildings, which are likely to have higher window U-values than required for Passivhaus. To prevent user dissatisfaction the designer will need to consider comfort, for example limiting glazing areas and careful positioning of heat emitters as well as heat distribution within rooms and the building as a whole.

Summer comfort requirements

AECB Building Standard certification requires summer overheating risks to be calculated using PHPP. Target values shall accord with current Passivhaus requirements.

Notes on compliance:

Compliance with the AECB Building Standard cannot be assumed unless the building has been modelled in PHPP, construction quality has been verified and the supporting data has been publicly declared.

Declaration takes place by:

You must create a user account at  the low energy buildings website  and create  a  project entry for your  building project. Once you have created your project listing  you  can begin to provide the evidence required for self certification of your project.

  • Uploading the   PHPP Verification sheet to the Low Energy Buildings Database.
  • Uploading a set of key construction details (drawn details and their photographic equivalent) to provide evidence of construction quality
  • Uploading a all other relevant data scheduled in checklist provided below

AECB Building Standard certification: Step-by-step

How are AECB Building Standard projects certified?

For your piece of mind AECB recommends that a suitably experienced person or a certified Passivhaus designer/consultant certifies the project. Ideally they are already a part of your design team, which means many costs associated with meetings and site visits can be absorbed without incurring significant additional cost.

Architects, Engineers and Consultants
A self-certification route has been developed whereby the self-certifier takes responsibility for certification and for underwriting the AECB Building Standard claim. The certifier may be a suitably experienced person or a certified Passivhaus designer/consultant, or the building’s energy assessor.

It is advised that you ensure a suitably experienced person or a certified Passivhaus designer/consultant, or the building’s energy assessor, has been appointed to act as certifier, and that design conformance has been demonstrated prior to commencing on site.

AECB Building Standard certification: Trading Standards and legal considerations

  • The claim that a building is designed to the AECB Building Standard can be independently verified.
    Where a certificate is provided by the AECB, the responsibility for certification rests with the professional signing this certificate and not with the AECB.
    The AECB reserves the right to recall any certificate in the event of proven malpractice or false claims.
  • Trading Standards and legal considerations:
    By making a project’s claim explicit and a matter of public record the self-certification process has been designed to provide a degree of consumer protection under trading standards – without the AECB having to get involved in quality control and legal matters.
  • Duty of care:
    Responsibility for certification and claims regarding building performance rest with the person signing the certificate. There is also a duty of care placed on the client to ensure that the consultant is competent and suitably insured.

The Role of the AECB in the certification process

Records: The AECB will retain electronic copies of such details as required to verify that a building meets the AECB Building Standard but it does not necessarily check for compliance.

Queries: The AECB reserves the right to query submissions at its own discretion. Self-certifiers shall respond to all queries to the AECB’s satisfaction. In the event of a failure to respond to queries within 20 working days then the AECB reserves the right to disallow the claim of AECB Building Standard compliance.

Declaration certificate: Though the AECB provides a declaration certificate it does not audit or take responsibility for the certification process. In this respect the responsibility for certification lies firmly with the certifying consultant making the declaration. To this end the declaration certificate, and all other relevant information must be completed by the certifying consultant.

In the event of a non-conformance claim the onus lies with the certifying consultant, not with the AECB.

What design tools are required?

If you want to start designing your AECB Building Standard project today you can purchase the latest version of PHPP here

Supporting evidence requirements

  Drawing & photographic record Drawings.PDF A4 format Photographs jpeg format.
1 All elevations of completed building One elevation per page. Scale bar to be included. one photo. for each elevation
2 Floor to wall junction – continuity of insulation visible
3 Floor to wall junction – airtightness measures visible    
4 Intermediate floor to wall junction – airtightness measures visible
5 Roof to wall junction – continuity of insulation visible
6 Roof to wall junction – airtightness measures visible    
7 Typical window in wall detail – jamb with wall insulation measures visible
8 Typical window in wall detail – jamb with airtightness measures visible    
9 Typical treatment of services penetration in fabric – with airtightness measures in place
10 Typical MEV or MVHR installation showing ducts & duct insulation    
11 Hotwater storage and pipework – showing tank and pipe insulation    
12 Windows/doors – showing opening light with seals and glazing spacer bars    
13 Air pressure test certificate (pressurisation and depressurisation results)  
14 PHPP verification sheet as pdf  
15 Copy of building users manual optional  

AECB Building Standard certification FAQ

If this page has not  answered your questions ,please read the FAQ or contact us at

 Low energy buildings

You can create a new user account at and create your low energy building project listing in order to self certify the project to the AECB Building Standard.

Low energy buildings project gallery
This can be found at the Low energy buildings website:

To browse projects aiming at or certified to AECB Building Standard click here.

To browse projects aiming at or certified to Passivhaus click here.

To browse projects aiming at or certified to EnerPHit click here.

If you require technical assistance or further information about the AECB Building Standard please contact us at

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