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 Requirements
Quick Reference TL;DR
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.
Ready to get started?
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:
- Self builds
- Developer plots
- Replacement dwellings
- 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 requirments
- An As Built SAP is needed once the project is finished. No project is built to the design specification. 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.
If your first result doesn't pass, we'll recommend the most cost-effective changes. All reasonable revisions are included until you achieve compliance.
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 perscriptive 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)
Don't have everything yet? We can work from reasonable assumptions and refine the SAP Calculation as your design develops.
New Build SAP Pricing
Fixed pricing per dwelling. Design SAP and As-Built are separate stages - pay for what you need.
Design Stage SAP
From £220
SAP 10 calculation for Part L compliance. Includes revisions until you pass.
Book online →SAP + Part O
From £320
Combined SAP and overheating assessment. Most new builds need both.
Get A Quote →As-Built + EPC
From £80
Final SAP update and EPC lodgement. Reduced rate when we did your Design SAP.
View full pricing →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?
Yes. Every new dwelling in the UK requires a SAP calculation to demonstrate Part L compliance. You need a Design Stage SAP before construction and an As-Built SAP at completion to get your EPC and final sign-off.
What are the new build SAP requirements?
New builds must meet Part L 2021 targets for Dwelling Emission Rate (DER) and Dwelling Fabric Energy Efficiency (DFEE). The SAP calculation checks your fabric U-values, heating system, ventilation and renewables against these targets.
How long does a new build SAP calculation take?
Most single dwellings are completed within 2-4 working days once we have your drawings and specification. Larger developments may take longer - we'll confirm timescales when we review your plans.
What documents do I need for a new build SAP?
Floor plans, elevations, sections, site plan showing orientation, construction build-ups, window schedule, heating specification and ventilation details. If you don't have everything yet, we can work from reasonable assumptions.
What happens if my new build fails SAP?
We provide clear recommendations ranked by cost-effectiveness - typically improving insulation, upgrading windows or adjusting the heating system. All reasonable revisions are included until you pass.
Do you provide As-Built SAP and EPC?
Yes. Once construction is complete, we update the SAP with your final specification and air test result, then lodge the EPC. If we completed your Design SAP, the As-Built is available at a reduced rate.
Will Building Control accept your reports?
Yes. All assessments are completed by an Elmhurst accredited OCDEA using approved SAP 10 software. Our reports are accepted by local authorities and approved inspectors across the UK.
Do new builds need Part O as well as SAP?
Yes. All new dwellings now require a Part O overheating assessment alongside SAP. Most pass using the simplified method, but some designs need dynamic simulation modelling. We offer combined SAP + Part O packages.
Ready to get your SAP Calculation?
All SAP calculations completed by an Elmhurst-accredited OCDEA and accepted by Building Control nationwide.