Project details
Service: Overheating assessments
Client: UK residential developer
Project: 22 new-build homes on brownfield redevelopment site
Location: Eastford Wharf, London E14
Regulation driver: Building Regulations Part O and TM59 compliance
ATSPACE team: Overheating assessment specialists, building compliance consultants
The headline result
ATSPACE delivered TM59 overheating assessments that enabled 22 new homes to achieve full compliance without any redesign delays.
The project was delivered on a constrained urban brownfield site with significant planning and design limitations. Despite high glazing ratios and challenging orientation, all units passed TM59 criteria first time, avoiding costly design revisions and maintaining the construction programme.
ATSPACE delivered:
Early-stage overheating risk review
TM59 dynamic thermal modelling
Unit-by-unit compliance assessment
Practical overheating mitigation advice
Building Control-ready compliance reporting
No redesign requirement or programme delay
Project overview
This project involved the delivery of 22 new residential homes on a tightly constrained brownfield site in East London. The scheme consisted of a mix of two- and three-bedroom houses arranged in a compact layout designed to maximise land use efficiency.
Due to planning requirements and architectural intent, the development included large areas of glazing and limited opportunities for external shading. While this improved daylight and aesthetic quality, it introduced a significant risk of overheating under Part O requirements.
ATSPACE was appointed during the detailed design stage when concerns were raised about potential TM59 compliance failures. The client needed assurance that the scheme could proceed without redesign delays, as the construction programme was already under pressure.
The key challenge was balancing design ambition with compliance requirements while maintaining the programme and avoiding costly late-stage changes.
Why the service matters
Overheating assessments are required to assess whether residential buildings are likely to experience excessive internal temperatures during hot weather conditions. This is particularly important in modern housing developments where airtight construction and high insulation levels can trap heat.
TM59 compliance is a recognised method for assessing overheating risk in residential dwellings. It uses dynamic thermal modelling to simulate internal conditions over time and determine whether homes remain within acceptable comfort limits.
This service is required by developers, architects, and consultants to demonstrate compliance with Part O of the Building Regulations. It is often reviewed by Building Control as part of the approval process.
Overheating assessments help ensure that:
Homes remain comfortable during warm periods
Solar gain is properly controlled
Ventilation strategies are effective
Designs meet regulatory requirements
If overheating assessments are left too late, projects can face redesign requirements, approval delays, increased costs, and potential failure to meet compliance standards.
The problem
When ATSPACE was appointed, the project was already facing several key risks linked to overheating performance.
The homes included large glazed elevations to maximise natural light, but this significantly increased solar gain risk. The urban location also meant limited opportunity for natural shading from surrounding structures.
Several issues were identified:
Inconsistent glazing specifications across design revisions
Limited coordination between architectural and M&E design teams
Unclear ventilation strategy for multiple dwelling types
High exposure of south-facing units
Late design changes not reflected in modelling assumptions
There was also significant programme pressure. The client needed TM59 compliance confirmed quickly to avoid delays to construction milestones.
Without intervention, several homes were at risk of failing overheating criteria, which would have required design changes and potential delays.
What ATSPACE was asked to do
Carry out TM59 overheating assessments for all 22 homes
Identify overheating risks across all dwelling types
Confirm compliance with Part O requirements
Review architectural and environmental design data
Provide practical mitigation strategies to avoid redesign
Support design team with compliance guidance
Deliver Building Control-ready reporting
Our approach
Step 1: Understanding the compliance requirement
ATSPACE confirmed that full TM59 dynamic thermal modelling was required under Part O due to the building type, glazing levels and urban exposure. We aligned the assessment methodology with Building Control expectations from the outset.
Step 2: Reviewing design information and risk factors
We reviewed all architectural drawings, glazing specifications, ventilation assumptions and dwelling layouts. This process identified inconsistencies that needed to be resolved before modelling could proceed accurately.
Step 3: Practical mitigation before final assessment
Before completing the modelling, ATSPACE provided targeted recommendations to reduce overheating risk, including:
Adjusting glazing performance values in high-risk elevations
Improving natural ventilation pathways through dwelling layouts
Optimising window opening assumptions
Refining solar gain inputs where appropriate
These measures were practical and avoided any requirement for redesign.
Step 4: TM59 compliance reporting
ATSPACE completed full dynamic thermal modelling and produced a structured TM59 overheating assessment report. The report demonstrated compliance across all 22 homes and provided clear evidence suitable for Building Control submission.
Real issues we faced and how we solved them
Issue A: High solar gain in south-facing homes
Several dwellings showed elevated overheating risk due to orientation.
How ATSPACE helped:
We adjusted glazing performance inputs and improved ventilation assumptions, bringing all units within compliance limits.
Issue B: Inconsistent design revisions
Multiple drawing sets contained conflicting glazing and ventilation data.
How ATSPACE helped:
We coordinated final design inputs with the client team before modelling to ensure accuracy and consistency.
Issue C: Limited shading opportunities
The urban brownfield site offered no meaningful external shading options.
How ATSPACE helped:
We optimised internal design assumptions and ventilation strategies to offset solar exposure without physical redesign.
Issue D: Tight programme constraints
The project required fast turnaround to avoid delaying construction.
How ATSPACE helped:
We prioritised high-risk dwellings first and streamlined modelling delivery while maintaining full compliance accuracy.
Results
TM59 compliance achieved for all 22 homes
No redesign required at any stage
No delay to construction programme
Full Building Control-ready overheating report issued
All dwellings passed Part O criteria first time
Overheating risks successfully mitigated
Client retained full programme certainty
What this project proves
This project demonstrates that TM59 compliance can be achieved without redesign delays when overheating risks are identified and managed early.
Overheating assessments are not just a regulatory requirement, but a critical design tool that helps protect project programmes and avoid costly late-stage changes.
When managed correctly, they allow teams to:
Maintain design intent
Avoid construction delays
Reduce compliance risk
Deliver comfortable, regulation-compliant homes
Early engagement is key to avoiding unnecessary redesign and ensuring smooth project delivery.
Mini FAQ
What is TM59 compliance?
TM59 compliance refers to meeting overheating risk criteria in residential buildings using dynamic thermal modelling methods.
Do all new homes need overheating assessments?
Most new residential developments require overheating assessments to demonstrate compliance with Part O.
Can TM59 compliance be achieved without redesign?
Yes, with early analysis and practical mitigation strategies, compliance can often be achieved without major design changes.
What causes overheating in new homes?
Common causes include high glazing ratios, poor ventilation design, and urban heat exposure.
When should overheating assessments be done?
They should be carried out during the design stage to avoid delays and redesign risks.
Can ATSPACE help with existing design issues?
Yes, ATSPACE regularly supports projects that need compliance achieved without affecting construction programmes.
Call to action
Need help achieving TM59 compliance for your housing scheme?
ATSPACE works with developers, architects and consultants to deliver clear overheating assessments that avoid redesign delays and support smooth Building Control approval. Send your project details and we will confirm requirements and next steps.
