Melin Energy Consultants were appointed by Kallarview Homes to undertake Part O overheating assessments for a development of 10 apartments located on Cambridge Road, Bromley.
The scheme comprised a mix of 1, 2 and 3-bedroom flats arranged across multiple floors, with three apartments per floor and heated communal corridors. Mechanical Ventilation with Heat Recovery (MVHR) was proposed throughout the development as part of the building services strategy.
Given the development’s location within Greater London, careful consideration was required to address overheating risks associated with the Urban Heat Island Effect and ensure full compliance with Approved Document Part O.
Understanding The Challenge
During our assessment, we identified a significant compliance challenge affecting the ground-floor apartments.
Several bedrooms had been designed without traditional external windows, relying instead on external side-hung doors for ventilation. Whilst these doors provided access to external air, Part O modelling assumptions do not permit external doors to be considered open overnight for security reasons.
This created a particular challenge in demonstrating compliance with Criterion 2 of Part O, which limits the number of hours a bedroom can exceed an operative temperature of 26°C between 10pm and 7am. In London developments, where external temperatures are elevated by the Urban Heat Island Effect, achieving compliance without adequate night-time ventilation can be particularly difficult.
Our Approach
Rather than simply identifying the problem, we worked closely with the client to develop practical solutions that would allow the project to progress without unnecessary redesign.
We provided clear guidance on the regulatory requirements and explained why the proposed design struggled to satisfy the overnight overheating criteria. Alternative ventilation strategies were discussed and reviewed collaboratively with the design team.
The client subsequently proposed revised window opening arrangements for the affected ground-floor bedrooms. We promptly remodelled the apartments using the proposed amendments and carried out a new series of Part O simulations to assess their effectiveness.
Throughout the process, we maintained regular communication with the client, ensuring they fully understood the results and the impact of each design change before decisions were made.
Delivering A Compliant Solution
The revised window design successfully addressed the ventilation concerns within the ground-floor apartments and enabled the development to achieve compliance with Part O requirements.
Further analysis also identified overheating risks within several top-floor apartments due to extensive glazing areas. To mitigate these risks, solar control glazing was introduced, and we provided the client with clear guidance on the required glazing performance and g-values needed to achieve compliance.
Recognising the wider implications of these changes, we also advised the client that the amended glazing specifications could impact the project’s SAP calculations and recommended that the energy assessments be reviewed accordingly.
Outcome
Through close collaboration and a proactive approach to problem-solving, the project successfully achieved compliance with Part O overheating requirements without significant disruption to the design programme.
By identifying issues early, assessing multiple design options and providing clear technical guidance throughout the process, Melin Energy Consultants helped the client navigate a complex compliance challenge and reach a practical, cost-effective solution.
The client was particularly pleased with the level of communication, responsiveness and support provided throughout the project, highlighting the value of having an experienced consultant involved from the early design stages.
Services Provided
- Part O Overheating Assessments
- Dynamic Overheating Analysis
- Design Team Consultation
- Ventilation Strategy Review
- Regulatory Compliance Advice
- Technical Reporting
- Ongoing Design Support