Agar Grove - Camden's Passivhaus Living Lab

Camden Council's has demonstrated a pioneering commitment to Passivhaus social housing with its Agar Grove development, targeting 345 affordable Passivhaus homes. Begun in 2015, the development is being rolled out in phases, each phase iteratively building on lessons from the previous one. Phase 1C, the third phase of the development, is now completed and Passivhaus certified.

Agar Grove, Phase 1C. Image credit: Francesco Montaguti

Replacing existing 1960s housing blocks, the Agar Grove development is being built for new and existing tenants in the London Borough of Camden. Delivered over 6 phases, each iteration is offering scope for learning and improvement for the delivery teams. The phasing for the programme has been based around a 'single decant' process to allow residents to stay on site and move straight into their homes once complete. Phase 1C, the third phase of the development, is now completed and certified. The 125-home development is made up of two six-storey buildings and is tenure-blind, ensuring equal quality across housing types.

Learning lessons from the previous Agar Grove phases, a different approach to services and heating systems has been developed to respond to both post occupancy evaluation (POE) from earlier phases of the Agar Grove development, and to the wider decarbonisation of the UK's electricity supply.

Passivhaus Trust members have played a prominent role in the Phase 1C project. PHT member Hawkins\Brown is lead architect on the project, working with with PHT Patron Max Fordham as Passivhaus consultant and M&E Designer. PHT member QODA Consulting has been supporting the contractor on Passivhaus compliance, and PHT Patron WARM as Passivhaus Certifier.

Key stats

Construction: Concrete
Number of homes: 125
TFA: 2663 m² (Block I) & 6033 m²(Block JKL)
Build start date: 2021
Completed: 2024
Certified: Passivhaus, 2024

Agar Grove 1c, Camden. Image credit: Francesco Montaguti

The regeneration of this estate is helping us to build hundreds of new environmentally sustainable homes which will benefit both current and future residents... 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.

Michelle Christensen, Senior Development Manager, Camden Council

Construction

The two buildings that make up Phase 1C, Block I and Block JKL, are six-storey concrete frames. The construction method is a typical concrete frame with masonry skin that deviates from the norm by placing the airtightness line (15mm parge coat) within the cavity; this adds robustness to the longevity of the airtightness line by removing the risk of user damage during occupation.

$Wall make-up. Image credit: Hawkins\Brown$	$Checking airtightness tape below window. Image credit: Hawkins\Brown$
$Cavity wall detail. Image credit: Hawkins\Brown$	$Wndow installation. Image credit: Hawkins\Brown$

A fully-filled cavity allowed to maximisation of the thermal performance of the wall . The insulation being blown in also helped speed up construction. On Block JKL, solariums (winter gardens) are utilised to reduce the thermal line area by internalising inset balconies and raising the window threshold to simplify the thermal and airtightness junctions at slab level.

Agar Grove 1C, Camden. Image credit: Tim Crocker Photography

The Agar Grove masterplan provides affordable homes for new and existing tenants in the London Borough of Camden that put energy performance and tackling fuel poverty top of the agenda.

Phil Catcheside, Partner, Hawkins\Brown

U-values

Roof: 0.062 W/m²K (Block I) & 0.090 W/m²K (Block JKL)

Brown roof system, 250mm PIR warm roof Insulation, concrete slab

Agar Grove 1C, Camden. Image credit: Francesco Montagut

Wall: 0.148 W/m²K (Block I) & 0.150 W/m²K (Block JKL)

102.5mm brickwork, varying cavity (between 150, 200 and 250mm) with full fill blown mineral wool cavity wall insulation, 15mm parge coat on the inside of the cavity face, 140mm autoclaved aerated concrete (AAC), internal drylining system.

Floor: 0.133 W/m²K (Block I) & 0.134 W/m²K (Block JKL)

65mm floating screed, 25mm EPS Insulation, 250mm concrete slab, 200mm below ground XPS Insulation, heave protection

Building performance

Designed energy performance

Block I

Block JKL

Airtightness n₅₀ (≤ 0.6ACH @ 50 Pa)

0.6 @ 50 Pa

Space Heating Demand (≤ 15 kWh/m².a)

14 kWh/m².a

15 kWh/m².a

Heating Load (≤ 10 W/m²)

9 W/m²

Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)

79 kWh/m².a

73 kWh/m².a

*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria.

Agar Grove 1C, Camden. Image credit: Francesco Montaguti

Phase 1C is the first all-electric phase of Agar Grove and we have been able to deliver these Passivhaus buildings using products and technologies that are common to buildings of this typology in the UK – demonstrating that low-energy Passivhaus projects aren’t at odds with mainstream construction.

Gwilym Still, Director - Passivhaus, Max Fordham

Services

Heating strategy: Unlike previous phases at Agar Grove, Phase 1C uses an innovative heating system uses an ambient loop system . Each building has a stand-alone air source heat pump system on the roof of each block generate tepid water at ≈25°C. This circulates through the building with minimal heat loss (helping to avoid both wasted energy and overheating in circulation spaces), and feeds water-to-water heat pumps located in each home. These second heat pumps generate warm water for space heating, and hotter water for domestic use: showering, bathing etc. The ambient loop system was chosen following a team options appraisal, including testing a more standard heat network, and monitoring data from other heat network systems. Summer comfort modelling against future weather files was part of the decision: the ambient loop arrangement gives a low-disruption route to deliver cooling in the future, to ensure climate resilience. .

Ventilation strategy: Unlike one of the previous phases, each home in Phase 1 has its own MVHR unit, generally located close to the thermal line of the building.

Summer comfort strategy: The ambient loop system used for heating the homes also has the potential to add cooling if needed in the future. In addittion summer comfort was carefully modelled in PHPP, which affected glazing size and design as well as the inclusion of shading.

Handover material shared with occupants

Challenges & lessons learned

Orientation: The orientation of Blocks I and JKL is not predominantly south‑facing and responds to an existing urban context that was never designed to maximise winter solar gains. As such, the scheme deviates from the Passivhaus rulebook, which typically stipulates that the main building façade should face south. Here, the elevations face north, south‑east and west. As a result, the project team needed to work the building detailing harder to ensure more heat was retained during winter that would ordinarily have been offset by winter sun.
Complex detailing: The form of Block I features inset balconies and an angled building form that creates a dynamic aesthetic but also introduces complex detailing, with a varying thermal line that does not stack. This resulted in additional details to ensure airtightness and thermal continuity.

Solariums: The project team changed from external inset balconies to internalised solariums to simplify and shorten the thermal line. This significantly benefited the PHPP and still provides residents with the feel of an outdoor space without the associated heat losses. Residents have commented on how much they enjoy these spaces.
Form factor: Phase 1C tested the boundaries of what can be achieved with a less‑than‑efficient form factor while still meeting PHPP requirements. The design is dynamic, with terraces, inset balconies, angled building forms and bespoke window details (including the diamond windows on JKL) but still was able to achieve Passivhaus certification.

Collaboration: Phase 1C reaffirmed the relationship between the design and construction teams, whodrew on each other’s Passivhaus experience to produce solutions that met PHPP requirements while remaining viable for construction and on‑site phasing. The benefit of this collaborative relationship is already evident on Agar Grove Phase 2A.

Innovative heating & cooling strategy: The project team developed a future-proof heating system using an ambient loop system combined with individual water to water heat pumps for each home. The combination of the two systems helps minimise heat loss during circulation, as well as offering a route to delivering cooling to the homes in the future for climate resilience.

$Solarium at Agar Grove 1C, Camden. Image credit: Hawkins\ Brown$

Agar Grove, Phase 1C. Image credit: Francesco Montaguti

Architect’s view

Agar Phase 1C is the next chapter in the story of the Agar Grove Estate regeneration. All 125 units delivered in this phase meet 100% Passivhaus standards using a fabric‑first approach, making it one of the largest UK Passivhaus developments.

The scheme’s orientation follows the established urban fabric and is therefore not predominantly south‑facing — going against the typical Passivhaus design rule book — yet still achieving the required standard. Homes feature active frontages, double‑height communal entrances, and naturally lit stairwells. Bedrooms face courtyards or are located on upper floors. Learning lessons from previous phases, the thermal envelope has been simplified, reducing the area exposed to the elements. Recessed balconies are glazed to form solariums, and large triple‑glazed windows enhance comfort.

Ground‑floor flats and maisonettes have private gardens, and some units benefit from roof terraces. Communal gardens, play areas, and growing spaces are secure and wildlife‑friendly. High‑quality brick and GRC façades complement Camden’s character. Pedestrian navigation is improved through connected routes, softened highway impacts, and landscaped buffers. The design, shaped by resident consultation, follows a streets and squares concept with street‑level entrances and liveable spaces.

Resident feedback has been overwhelmingly positive and sets the stage for the next chapter in the estate’s development.

,
Matt Harrall, Senior Architect and Passivhaus Designer, Hawkins\Brown

Key team

Architect: Hawkins\Brown, Mae
Passivhaus Consultant: Max Fordham
Passivhaus compliance support: QODA Consulting

Contractor: Hill Partnership
Structural engineer: Price & Myers
M&E consultant: Max Fordham
Passivhaus Certifier: WARM

Agar Grove demonstrates that delivering Passivhaus at scale is about more than repeating a successful design. Each phase has provided an opportunity to test new ideas, evaluate performance, gather resident feedback and refine both design and construction. From simplifying the thermal envelope to developing an innovative all-electric heating strategy, the programme shows how continuous learning can improve outcomes for residents while making future Passivhaus projects more efficient to deliver.

As more local authorities and housing providers embark on large-scale Passivhaus programmes, the value of sharing these lessons cannot be overstated. Join us at this year's Passivhaus Conference in November to hear directly from councils, housing associations and project teams delivering Passivhaus at scale across the UK. A limited number of complimentary tickets are available for public sector clients. Or become part of a Passivhaus Client Club to exchange practical experience, learn from completed projects and help shape the next generation of high-quality homes.