Standard 3.28 (Scotland) & Approved Document O (England)

Overheating Risk Assessments for New Build Dwellings

Every new dwelling in Scotland and England now needs a formal assessment of summer overheating risk before Building Warrant or Building Regulations completion — Standard 3.28 of the Domestic Technical Handbook in Scotland, Approved Document O (Part O) in England. It's a separate assessment from your SAP calculation, using its own methodology, and it isn't something you can skip for a new dwelling in either jurisdiction. A desktop service based on your drawings and glazing specification, delivered UK-wide with no site visit needed, backed by 45 years' experience in Building Control and Building Standards.

Get a Quote How It Works

Why Get a Proper Overheating Assessment, Not an Afterthought

Overheating risk is now assessed separately from SAP, using its own methodology — and it's easy to leave it too late in the design process to fix cheaply.

Correct Methodology for Your Jurisdiction

Standard 3.28 assessment for Scottish new builds, or the Part O simplified method for English new builds — checked against the right criteria for your site.

45 Years' Regulatory Insight

Prepared by a Chartered Building Surveyor with 45 years in Building Control and Building Standards, including senior local authority roles reviewing exactly this kind of submission.

Elmhurst-Accredited Assessor

Current accreditation as an Elmhurst OCDEA (On-Construction Domestic Energy Assessor), keeping pace with the latest overheating methodology in both jurisdictions.

Fixed Fee, Fast Turnaround

Clear pricing agreed up front, with no surprises — and a quick turnaround so the assessment doesn't hold up your Building Control or Building Warrant submission.

How It Works

A desktop process based on your design drawings, timed to catch problems while they're still cheap to fix.

Send Drawings & Glazing Details

Email floor plans, elevations, glazing specification and orientation, plus your ventilation strategy (natural, MEV, MVHR) and any solar shading proposed.

Overheating Risk Assessment

I run the assessment using the correct methodology for your site — Standard 3.28 in Scotland, or the Part O simplified method in England.

Report & Recommendations

A written assessment confirming compliance, or — where risk is flagged — specific, practical changes to bring it within limits: shading, glazing specification, or ventilation.

Support Through Building Control

If Building Control or your Verifier raises reasonable queries while the application is being determined, I'm on hand to help you respond.

Who This Is For

Self-builders and homeowners building a new dwelling in Scotland or England
Small developers and architects needing overheating sign-off for a new build scheme, single plot or multiple house types
Anyone whose Building Control surveyor or Verifier has queried overheating risk on a new dwelling submission
Designers who want an overheating check early, while shading, glazing and ventilation can still be adjusted cheaply

This service is for new build dwellings. It doesn't (currently) cover:

Extensions in England — Approved Document O (Part O) explicitly excludes extensions and conservatories added to an existing dwelling, so there's no regulatory requirement here. If you'd still like a voluntary overheating check on a heavily glazed extension, that's covered under my Highly Glazed Extension Assessment service instead.
Conversions — Scotland's Standard 3.28 applies to conversions only "as far as reasonably practicable", and England's Part O doesn't apply to a change of use at all. Get in touch if you'd like this checked as part of a conversion EPC or Building Standards consultancy instruction.
Full CIBSE TM59 dynamic thermal modelling — needed where a dwelling can't rely on openable windows for cooling, or where the simplified method doesn't pass. This requires specialist simulation software; get in touch and I can point you in the right direction.

Pricing

A fixed fee for a single, straightforward new build dwelling.

£164

Simplified Method

Standard 3.28 assessment (Scotland) or Part O simplified method (England) for a single dwelling
Written confirmation of compliance, or the changes needed to achieve it
Support responding to reasonable Building Control or Verifier queries

Get Started

This is the fee for a single, straightforward dwelling. Multiple plots and developments of 5+ dwellings (where house types are repeated) are quoted separately — discounts are available for repeat house types across a development. Get in touch with your design stage drawings for an exact quote.

Frequently Asked Questions

Is this the same as my SAP assessment?

No. Overheating risk used to be considered within SAP but is now assessed separately, using its own methodology — Standard 3.28 in Scotland, Approved Document O in England. You'll typically need both a SAP assessment and an overheating assessment for a new dwelling.

Does this apply to my extension?

Not in England — Approved Document O explicitly states it does not apply to extensions or conservatories added to an existing dwelling. In Scotland, Standard 3.28 is written around new dwellings; if you're planning a substantial extension and want peace of mind, get in touch and I'll advise honestly on whether an assessment is needed or worth having voluntarily.

Does this apply to a conversion?

Only partially. Scotland's Standard 3.28 applies to conversions "as far as reasonably practicable", with a rule that overheating performance can't be made worse than before the conversion. England's Part O doesn't apply to a change of use at all. Get in touch if you'd like this considered as part of a conversion project.

Do you offer full CIBSE TM59 dynamic thermal modelling?

Not currently. This service covers the simplified method, which checks glazing area, orientation and ventilation openings against set limits and satisfies Standard 3.28 or Part O for most new build dwellings. Some dwellings that can't rely on openable windows for cooling — certain flats, for example — or that don't pass the simplified method, need full CIBSE TM59 dynamic thermal modelling instead, which requires specialist simulation software. Get in touch and I can point you toward someone who offers that.

Do you need to visit the site?

No. This is a desktop exercise based on your drawings, glazing specification and ventilation strategy.

What do you need from me to get started?

Scaled floor plans and elevations, glazing specification and orientation, and your ventilation strategy (natural, MEV, MVHR) and any shading proposed. Get in touch and I'll confirm exactly what's needed for your project.

Do you offer discounts for developments with multiple plots?

Yes. Where house types are repeated or specifications are consistent across plots, we offer reduced rates per dwelling to reflect the efficiencies of assessing similar types together.

Do you cover Scotland and England?

Yes. The assessment is carried out against the applicable framework — Standard 3.28 of the Building (Scotland) Regulations, or Approved Document O in England — based on where your site is.

What if Building Control or my Verifier asks for more information?

Support responding to reasonable queries is included, so the assessment doesn't hold up your Building Control or Building Warrant submission.