New-Build SAP Assessments and Part L Compliance
L1A SAP Calculations London
Professional design-stage and as-built SAP calculations for new-build houses, flats and residential developments throughout London and Greater London.
L1A SAP Assessments in London
If you are constructing a new home in London, an L1A SAP Calculation is required to demonstrate compliance with Part L of the Building Regulations.
One Stop Consult provides fast, accurate and cost-effective SAP assessments for homeowners, developers, architects and builders working on new-build residential projects.
Support is available from the early design stage through to the final as-built assessment, Energy Performance Certificate and supporting Building Control documentation.
L1A SAP Calculations Across London and Greater London
We support projects throughout Central London, Westminster, Kensington, Chelsea, Camden, Islington, Southwark, Lambeth, Greenwich, Stratford, Wimbledon and Ealing.
Nearby coverage also includes Croydon, Bromley, Barnet, Enfield, Harrow, Hounslow, Romford and surrounding Greater London areas.
What Is an L1A SAP Calculation?
An L1A SAP Calculation is the energy assessment required for newly constructed dwellings under Part L of the Building Regulations.
Government-approved SAP software is used to predict the energy performance of the proposed home and determine whether the design satisfies the applicable efficiency requirements.
The assessment is normally completed before construction begins and updated at completion using the final as-built specification.
What Does the Assessment Consider?
SAP considers the dwelling as a complete energy system rather than reviewing only one element of the construction.
Accurate drawings and specifications help the assessor model the proposed home and identify the most effective route to compliance.
External walls, roofs and floors
Windows, doors and rooflights
Thermal bridging
Heating and hot-water systems
Ventilation strategy
Air permeability
Lighting efficiency
Renewable technologies
L1A SAP Services
What Our London Service Can Include
01
Design-Stage SAP Calculations
Assessment of the proposed new dwelling before construction to confirm the design can satisfy Part L.
02
As-Built SAP Calculations
Final assessment based on the materials, systems and construction actually installed.
03
Energy Performance Certificates
EPC preparation and lodgement following completion of the final SAP assessment where applicable.
04
Part L Compliance Reports
Clear compliance documentation suitable for submission to Building Control.
05
TER and DER Calculations
Comparison of the dwelling's predicted emissions against the applicable target performance.
06
Fabric Energy Efficiency
Assessment of the building fabric and energy demand against the required standard.
07
Renewable Technology Advice
Review of suitable renewable measures where they form part of the proposed compliance strategy.
08
U-Value Support
Assessment of proposed construction build-ups where U-value confirmation is required.
09
Air Permeability Guidance
Advice on the design air-tightness target used within the SAP model and final testing requirements.
Design-Stage SAP Calculations
The design-stage assessment should ideally be completed before construction begins.
This allows insulation, glazing, heating, ventilation and renewable technologies to be reviewed while changes remain practical and cost-effective.
Where the first assessment does not achieve compliance, the assessor can recommend suitable improvements for consideration by the project team.
As-Built SAP and EPC
Once construction is complete, the SAP assessment is updated to reflect the final materials, products and building services installed.
Any changes made during the build should be reported to the assessor, including revised insulation, glazing, heating, ventilation, renewable systems or air-test results.
Following a compliant final assessment, the Energy Performance Certificate can be prepared and lodged where required.
Typical London Projects
New-Build Projects We Commonly Assess
Improving the SAP Result
Practical Compliance Measures
Where the initial design does not satisfy Part L, the assessor can review practical options with the project team.
Improved Insulation
Enhanced wall, roof or floor performance can reduce heat loss and improve the overall result.
Better Glazing
Improved window and door performance can reduce fabric losses.
Reduced Thermal Bridging
Better junction details can improve the dwelling's fabric energy performance.
Efficient Heating and Hot Water
Suitable low-carbon or high-efficiency systems can improve predicted energy and emissions performance.
Improved Airtightness
A sensible design target can reduce uncontrolled heat loss, provided ventilation is properly designed.
Solar PV
Photovoltaic panels may support compliance where appropriate for the building and energy strategy.
Our L1A SAP Assessment Process
We make the assessment process clear from the first enquiry through to the final EPC.
Send us the latest drawings and project specification.
The assessor reviews the fabric, glazing and building services.
The design-stage SAP calculation is completed.
Any required compliance improvements are identified.
The assessment can be updated as the design develops.
Final construction information and test results are provided.
The as-built SAP and EPC are completed where applicable.
1
Send Your Information
Provide the architectural drawings, construction specification and building-services details.
2
Design Review
Review the insulation, glazing, heating, ventilation and renewable strategy.
3
Design-Stage SAP
Model the proposed dwelling and assess compliance with Part L.
4
Construction Updates
Incorporate relevant changes made during the build.
5
As-Built SAP and EPC
Complete the final assessment and prepare the EPC where required.
Why Choose One Stop Consult?
Our assessors work on projects ranging from individual self-build homes to large multi-unit residential developments.
We provide clear calculations, practical design advice and responsive support throughout the design and construction process.
Experienced SAP assessors
Fast turnaround times
Fixed competitive pricing
Current Part L compliance support
Design-stage and as-built service
Practical improvement advice
Building Control coordination
London and nationwide coverage
Information Required for a Quotation
Provide the full London project address, number of dwellings, development type and current design stage.
Please upload the architectural plans, elevations, sections, site plan and available construction specification.
Window, heating, hot-water, ventilation and renewable-system information should also be supplied where available.
Related London Services
Other Services Your Project May Require
Important L1A SAP Information
SAP results depend on the accuracy of the drawings, construction specification and building-services information provided. Changes made during construction can affect compliance and should be reported to the assessor.
Final assessments may require evidence including photographs, product information, air-test results and commissioning records. One Stop Consult provides consultancy and coordination support through experienced SAP assessors.
Frequently Asked Questions
L1A SAP Calculations London FAQs
What is an L1A SAP Calculation?
It is the Part L energy assessment required for newly constructed residential dwellings.
When should the SAP calculation be completed?
The design-stage assessment should ideally be completed before construction begins.
What information do you need?
We normally require architectural drawings, construction specifications, glazing details, heating, hot-water and ventilation information.
Will I receive an EPC?
Where applicable, the EPC is prepared following completion of the compliant as-built SAP assessment.
Can you help if the design does not comply?
Yes. The assessor can recommend practical improvements to insulation, glazing, heating, airtightness or renewable systems.
Do I need an air tightness test?
New dwellings commonly require a final air permeability result for the as-built SAP assessment, subject to the applicable testing requirements.
Do you assess housing developments?
Yes. We work on individual dwellings and multi-unit residential schemes of varying sizes.
Do you cover all of London?
Yes. We provide L1A SAP calculations throughout London, Greater London and the wider Greater London.
What information is needed for a quotation?
Provide the address, dwelling numbers, drawings, design stage and available construction and service specifications.
Request Your Free L1A SAP Calculations Quote
Complete the form below with the London project address, number of dwellings and current design stage. Upload the latest drawings, construction specification and available heating and ventilation details so our team can review the requirement and provide an appropriate quotation.