Part L Compliance for New Dwellings
SAP Calculations for New Builds
Every new home needs a SAP calculation for Building Control. Design Stage SAP before you build, As-Built SAP and EPC at completion.
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New Build SAP Calculations
Do I need SAP for a new build?
Yes. All new dwellings need SAP for Part L compliance. No exceptions.
What about Part O?
Also required. All new homes need an overheating assessment alongside SAP.
How long does it take?
Typically 2-4 working days once we have your drawings.
What documents do I need?
Plans, elevations, construction details, heating spec, window schedule.
What if my design fails?
We'll recommend the cheapest fixes. Revisions included until you pass.
Do you lodge the EPC?
Yes. As-Built SAP + EPC lodgement at completion.
Upload your plans and we'll confirm what you need and provide a fixed quote.
Do I Need a SAP Calculation for My New Build?
Every new dwelling in the UK requires a SAP calculation to comply with Part L of the Building Regulations.
This applies to all new homes including self builds, developer plots, replacement dwellings and new flats.
A SAP Calculation is required by Building Control at two stages during the project:
- A Design SAP is needed before construction starts to prove the design can meet Part L requirements
- An As Built SAP is needed once the project is finished. This final SAP Assessment is proof that the constructed dwelling meets the Part L targets.
SAP for Self Builders
If you're building your own home, SAP is one of the first things Building Control will ask for. The Design Stage SAP proves your plans meet Part L energy targets before you break ground.
Self builds often have more flexibility than developer homes. You can choose better insulation, efficient heating systems, or renewables to hit the targets. We work with self builders to find the most cost effective specification that passes without over engineering.
Self Builder? Start Here
Upload your drawings and we'll review your specification, flag any issues early, and provide a fixed quote.
Upload Plans for Quote →New Build SAP Requirements
The SAP assessment models your entire dwelling to calculate its predicted energy use, carbon emissions and fabric performance. These are compared to a notional dwelling, the same size and shape of your design that passes the Part L SAP Requirements.
Fabric Performance
- ✓ Wall, floor and roof U-values
- ✓ Window and door performance
- ✓ Thermal bridging at junctions
- ✓ Air tightness
Building Services
- ✓ Heating system efficiency
- ✓ Hot water generation
- ✓ Ventilation strategy
- ✓ Lighting and controls
Renewables
- ✓ Solar PV contribution
- ✓ Solar thermal systems
- ✓ Heat pumps
- ✓ Battery storage
Compliance Outputs
- ✓ Dwelling Emission Rate (DER)
- ✓ Primary Energy Rate
- ✓ Fabric Energy Efficiency
- ✓ BREL / BRWL and EPCs
How to Pass SAP for a New Build
Part L 2021 is tougher than previous versions, but most designs pass with sensible specifications. Here's what typically makes the difference:
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1
Good fabric performance
Walls around 0.18 W/m²K, floors 0.13, roofs 0.11. Standard for most modern builds.
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2
Efficient heating
Modern combi boiler or heat pump. Gas boilers still work but need better fabric to compensate.
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3
Controlled ventilation
MVHR recovers heat from extract air. dMEV is a simpler alternative that can help in some homes.
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4
Consider renewables
Solar PV is often the cheapest way to close a gap. A few panels can make the difference.
Do New Builds Need Part O?
Yes. Since June 2022, all new dwellings require a Part O overheating assessment alongside SAP. This checks that bedrooms and living spaces won't overheat during summer.
Most homes pass using the simplified method. The Part O simplified method is a prescriptive check based on glazing areas, orientation and ventilation. Designs with large glazing, single-aspect layouts, or limited ventilation may need dynamic simulation modelling (TM59).
Combined SAP + Part O
We offer SAP Calculations and Part O Assessments as standalone services, but if you need both for your project we'll add a discount.
Upload Your Plans →How the New Build SAP Process Works
We keep paperwork to a minimum and provide clear updates at each stage.
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1
Upload your drawings
Send floor plans, elevations, sections, site plan and your construction specification. We'll confirm what's needed and provide a fixed quote.
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2
We complete your Design SAP
We model your dwelling in SAP 10, check against Part L targets, and identify any changes needed. You receive a clear pass/fail result with recommendations.
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3
Submit to Building Control
Once you pass, we issue your Design SAP report and Part L compliance documentation.
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4
As-Built SAP and EPC
When the house is finished, we update the SAP with final specification and air test result, then lodge the EPC for sign-off and sale.
What We Need for Your New Build SAP
The more detail you provide upfront, the faster we can turn your SAP around. Most of this comes from your architect drawings and specification.
Drawings
- ✓ Floor plans with dimensions
- ✓ Elevations showing window positions
- ✓ Sections showing floor heights
- ✓ Site plan with north point
Construction Details
- ✓ Wall, floor, roof build-ups
- ✓ Insulation type and thickness
- ✓ Window and door schedule
- ✓ Frame types and U-values
Heating & Hot Water
- ✓ Boiler or heat pump model
- ✓ Radiators or underfloor heating
- ✓ Hot water cylinder details
- ✓ Controls and thermostat type
Ventilation & Renewables
- ✓ MVHR, MEV or extract fans
- ✓ Solar PV array size
- ✓ Battery storage (if applicable)
- ✓ Solar thermal (if applicable)
New Build SAP Pricing
Single plot pricing shown below. Multi-plot discounts available - get in touch for a quote.
Design or As-Built SAP
From £170
Per stage, per dwelling. Whether you need Design SAP, As-Built SAP, or both as standalone assessments.
As-Built + EPC Upgrade
From £80
For existing clients only. Reduced rate when we completed your Design SAP.
What's Included
- Full SAP 10 Design Stage calculation
- U-value calculations for all elements
- Thermal bridging assessment
- Heating and ventilation check
- Clear pass/fail result
- Unlimited design stage revisions
- BREL reports for Building Control
- As-Built SAP available at completion
- Email support throughout
New Build SAP - Frequently Asked Questions
Do all new builds need a SAP calculation?
What are the new build SAP requirements?
How long does a new build SAP calculation take?
What documents do I need for a new build SAP?
What happens if my new build fails SAP?
Do you provide As-Built SAP and EPC?
Will Building Control accept your reports?
Do new builds need Part O as well as SAP?
Ready to get your New Build SAP?
All SAP calculations completed by an Elmhurst-accredited OCDEA and accepted by Building Control nationwide.