The redevelopment of Agar Grove Estate sets a standard for social housing in the UK. As a "proof of concept" for large-scale Passivhaus developments in the UK, it has meaningfully tackled fuel poverty by reducing residents' fuel bills by 70% and has influenced changes to the London Plan's approach to district heat networks.

The brief

Working with architects Hawkins Brown, Mae and Architype, we are providing M&E, Sustainability and Passivhaus services for this 507-home estate regeneration scheme, which includes 345 Passivhaus homes.

The scheme involves the demolition of low-rise residential pavilions and the retention and deep retrofitting of the estate’s landmark Lulworth Tower. It was unanimously approved at planning, with the officer’s report remarking “exceptional in all aspects of design, from the masterplan right through to the detailed consideration of the doorstep experience”. The design has been driven by Camden’s overarching vision to tackle fuel poverty, and create a low maintenance, robust housing that fosters community and resident wellbeing.

The project has been led by the community. Extensive consultation led to the decision for a full redevelopment. The phasing was based around a “single decant” process to maintain the community spirit. This allowed residents to stay on site and move straight into their homes once complete.

We worked with the client to decide the energy strategy. This included analysis of various approaches, including Passivhaus, to determine which would provide the best value over the project lifespan. Assessments of the capital and running costs, risk of fuel poverty, and maintenance implications all fed into this process.

“Agar Grove is one of Camden Council’s Community Investment Programme’s flagship schemes. The regeneration of this estate is helping us to build hundreds of new environmentally sustainable homes which will benefit both current and future residents.

The most recent phase of the scheme provided 34 new council homes for local residents, these new homes are bigger and greener, giving families more space and helping to save on their bills. We are proud to be delivering much needed new homes that meet the highest standards, which are green, modern and have enough space for our families to grow.

We are so pleased with the most recent phase of Agar Grove and the opportunities it has provided for local families to move into bigger, safer and more secure accommodation where they can continue to thrive.” – Michelle Christensen, Camden Council

Planning permission for Passivhaus

At the time of Planning, 2013-2014, the widely held view was that all developments should connect to District Heat Networks with Combined Heat and Power (CHP). In pre-planning discussions, we proposed that a Passivhaus development with communal heating would perform better in-use than a non-PH development with district heating. The work drew attention to heat losses from district heat networks. Our research persuaded the Greater London Authority (GLA) to grant planning permission for one of the first large-scale residential Passivhaus projects in the UK. In 2018, the GLA announced adjustments to the London Plan, including a shift away from district heat networks with CHP systems.

Phase 1a

Phase 1a of the redevelopment was completed in 2018 and consists of 38 socially rented Passivhaus homes. Dwellings are dual aspect, enabling cross ventilation for effective natural cooling. Deep, south-facing balconies block peak summer solar gains and large window openings allow purge ventilation.

Renewable energy is provided via a PV array, exemplary air tightness helps to reduce heat losses and improve thermal comfort, and comprehensive Post Occupancy Evaluation - both measured (temperature, RH, C02) and resident feedback - has helped improve residents' comfort and experience. Measured data has shown that internal temperatures rarely dropped below 21^o in winter and only went above 26^o during the peak summer months, while resident feedback showed that all residents felt the air quality in their apartments was good and general comfort was a huge improvement on their previous flats. We also assisted Camden to create a clear and concise user guide to help residents understand and operate the controls in their apartments.

An innovative communal MVHR removes the maintenance burden from tenants, ensuring a continuous supply of fresh filtered air. Additionally, a mostly vertical riser strategy halved hot pipe lengths (compared to a traditional approach) so halved their contribution to overheating.

Measured data for Phase 1a gives an Energy Use Intensity of 62 kWh/m2/yr, which met the RIBA 2020 and 2025 Climate Challenge targets when first issued.

Phase 1a is fully occupied for socially rented accommodation. It is Passivhaus certified and Code for Sustainable Homes Level 4. © Jack Hobhouse

Dual Aspect flats in Phase 1a provide good summertime ventilation and have been designed to encourage deep daylight penetration.© Jack Hobhouse

External shading on Phase 1a outside the balcony line limits summertime overheating, while not restricting airflow. © Jack Hobhouse

Phase 1b & beyond

Phase 1b was completed in July 2021 and consists of 57 social and market-rate Passivhaus homes. Much of the M&E strategy has been duplicated, with the Passivhaus “fabric first” approach helping to achieve a high build quality. Individual MVHR units for each apartment provide fresh air and reduce heat loss, while solid materials, comprehensive insulation and robust detailing ensure good noise separation.

Phase 1c is currently under construction and will be all-electric, using an innovative ambient loop heat pump system.

"Agar Grove Estate's award-winning success - including a Passivhaus Trust Award, NLA Environmental Prize and CIBSE Building Performance Award - is testament to the efforts of the design team and Camden Council; all of whom have shown great commitment and ambition to deliver the first two phases of this trailblazing redevelopment. We're particularly proud of the CIBSE Building Performance Award as this celebrates the fact that the buildings really work!" - Scott Crease, Senior Partner at Max Fordham