Bollo Lane - Barratt London's Lo-E Passivhaus scheme

Places for London and Barratt London’s West London Partnership’s 457-home development in Ealing, targeting Passivhaus certification, represents a radical rethink of housing for London.

The Bollo Lane project involves plans to build 900 homes in Acton. Phase 2 involves 457 new homes, of which 50% will be affordable. Together, as the West London Partnership, Barratt London and Places for London are delivering circa 4000 Passivhaus homes. Places for London, the property arm of Transport for London, has a sustainable development framework with five overarching principles for its mission to build a more sustainable London.

The Bollo Lane scheme will be one the first projects rolling out Barratt London's new Lo-E Passivhaus homes, which is the result of intense R&D work to improve building performance, while minimising overheating and reducing dependency on active cooling systems. The low heat demand of the Lo-E homes negates the need to connect to district heating networks by offering a high performance 'fabric first' approach that aligns with the top tier of the Greater London Authority's London Plan energy hierarchy to ‘Be Lean’.

PHT member Beyond Carbon is the Passivhaus Certifier on the project.

Key stats

Construction: Concrete frame with SFS infill
Number of homes: 457
Expected build start date: 2026
Certification: Aiming for Passivhaus

Construction

Delivering solutions

Preventing overheating came up as a big issue for the Places for London team, and because installing active cooling in all new homes would have added a big additional expense to its schemes, they asked Beyond Carbon to undertake some research into other options, with the remit "if you had to start again – is there anything different you could do."

Housing Minister Steve Reed launches Bollo Lane project. Image credit: Barratt London

Rethinking window design was critical to this radical rethink, as was simplifying the MEP strategy, which also helped with keeping costs down. The biggest simplification was developing a prototype that did not need district heating and which minimised the cooling building services needed. Beyond Carbon undertook detailed research and came up with a number of recommendations:

Targeting Passivhaus certification
Solar optimised facades with simple, repeatable window designs and opening strategies
Secure ventilation
Simplified building services provision, using an exhaust air heat pump

Barratt London found that, apart from shifting from double glazing to triple glazing and installing MVHR, the U-value specification of the proposed homes was not a huge step-change from what they were currently delivering. By benefiting from a good form factor, the U-values required to meet Passivhaus certification were not vastly different. It is likely that, in some circumstances on larger buildings, the Future Homes Standard will require lower U-values than Passivhaus, though Bollo Lane was evaluated under Part L 2021. While Passivhaus airtightness targets are considerably more onerous than building regulations, the Barratt team is confident of delivering this, and realising the comfort and energy benefits of a high performance building.

Phase 2 of Bollo Lane and future homes delivered by the West London Partnership will be Passivhaus certified, enabling lower energy bills and excellent air quality for residents.

Lucy Attlee, Senior Design & Quality Manager, Places for London

The business case

In switching to the Lo-E Passivhaus design Barratt London and Places for London are anticipating to secure a number of benefits including:

Reduced rooftop plant
Increased PV and green roof opportunity
Reduced communal ground floor plant space
Increased number of apartments
Increased active ground floor frontage
Minimal snagging
Internal air quality benefits
Significantly lower running costs
Better comfort for residents
Greater resilience to heatwaves and to colder winters

Lo-E housing. Image credit: Barratt London/ Beyond Carbon

Our ambition with Lo-E Homes is to deliver homes that don’t just meet standards but meaningfully surpass them. This initiative reflects our deep commitment to innovation in housing and climate resilience. Lo-E Homes represent a new benchmark in high-density design, fusing functionality, sustainability, and comfort at scale.

Attzaz Rashid, Head of Design, Barratt London

Summer comfort strategy

The Bollo Lane site is linear with blocks running from the northwest to the southeast. There is expected to be little shading benefit to this facade because of the railway and low height buildings to the southwest of the site. To address the issue of excess solar gain, the window design is optimised with the southeast lower facades' bedroom windows being reduced in size and in some upper levels of facades a 300mm overhang was added.

Layout and location of Bollo Lane project. Image credit: Barratt London

Bollo Lane is exactly the kind of development we need and shows what’s possible when we work together to build the homes Londoners desperately need - more high-quality, affordable homes in well-connected places.

Steve Reed MP, Secretary of State for Housing

Attzaz Rashid, Head of Design, Barratt London

Services

An exhaust air heat pump system (EAHP) uses the exhaust air from a mechanical ventilation with heat recovery system (MVHR) to provide heating or cooling back into the apartment. When combined with an MVHR system and a water tank it can provide space heating and cooling, domestic hot water and fresh air for ventilation. The proposed EAHP system is able to meet all the heating needs of a typical dwelling without electric backup, meaning ultra-low running costs for residents, something the West London Partnership is keen to prioritise.

Bollo Lane, Action. Image credit: Barratt London

With high levels of affordable housing and one of the largest rollouts of Passivhaus homes in Europe, our West London partnership is setting the standard for the future of housebuilding in London.