Isle of Wight, UK
Sustainable homes, providing comfort with extremely low running costs
Cameron Close comprises of 16 family houses and 12 sheltered housing apartments, all of which are Passivhaus certified. The attractive and desirable development sits around inviting streets, with all homes having front and back gardens, while the apartments have generous, landscaped kitchen gardens giving plenty of private outdoor space.
All the homes perform extremely well environmentally and are considered excellent value for money by the local authority, considering the high level of specification, low running costs and long-term environmental benefits.
Highly specified homes that don’t lose sight of the architect’s vision
Cameron Close sits in the rural village of Freshwater on the Isle of Wight. The site was previously occupied by a Southern Housing Group sheltered housing scheme which was at the end of its life. All the existing homes on the site needed demolishing and we needed to provide homes which were low on energy consumption yet comfortable and healthy for people to live in.
Southern Housing Group did not originally intend for the scheme to be Passivhaus accredited. Yet the group wanted to consider how to respond to the net zero carbon agenda and looked at a fabric-first approach, over the use of micro-renewable technologies. This would enable the scheme to meet the stringent requirements needed to be eligible for grant funding from the Isle of Wight Council, under its Sustainable Community Strategy.
After the decision to go forward with the Passivhaus standard was made, we needed to alter our original stepped and staggered design. In the Passivhaus design, there is a limited number of external walls which you can use, so we needed to reduce these in order to minimise heat loss externally.
By amending the design, we developed a new semi-detached house typology for this project which strays from the typical Passivhaus design. The result is a Passivhaus-compliant community, that doesn’t compromise on quality, comfort or architectural vision.
Creating desirable homes whilst improving efficiency
The houses are semi-detached rather than terraced, which would be the most efficient form for Passivhaus design as it reduces heat loss between dwellings. We wanted to keep open views into the field and the trees and also felt that terraced housing would be unsympathetic to the local context.
Cameron Close was designed with a very distinctive gabled aesthetic unlike the norm for Passivhaus projects. This drove us to push what could be achieved in U values so that Passivhaus compliance could be achieved.
The homes are quite deep because we used attached walls as much as possible to comply with the Passivhaus standard. By using a semi-detached house type, we could include entrances at the side of the house which creates a more practical and efficient living space.
The homes are bathed in high levels of natural light from roof lights over the stairwells which also assists with the Passivhaus technical requirements for solar gain. Mechanical Ventilation with Heat Recovery (MVHR) systems were also used to recover and recycle heat for transfer around the home.
To reduce the risk of potential overheating, we incorporated south-facing, external sliding shades into the building.
The orientation of the homes has been considered to provide a feeling of security while maintaining privacy. The homes and apartments are of varying sizes, with flexible and adaptable interiors designed to encourage a sustainable, cohesive community.
challenges and solutions
Innovative design to achieve Passivhaus accreditation
We worked with Passivhaus Consultants, Low Energy Building Consultants (WARM) to ensure that the scheme would meet all the requirements of Passivhaus accreditation. Achieving Passivhaus accreditation required an exacting and meticulous approach but using a solid aircrete frame constructed from the Thin-Joint system meant at least the construction process itself was simplified.
A lot of housing associations have built residential schemes to Passivhaus principles, but have not gone down the full route of Passivhaus certification for all homes. We achieved accreditation by ensuring that everyone in our team, the contractor, the manufacturer and the client were all on board with all the procedures from the start and by taking great care with processes and materials. It was critical to the success of the project that everyone needed to embrace and understand the concept as attention to detail is paramount from the outset.
From a design point of view, Passivhaus is challenging, features such as porches and letterboxes require innovative solutions to provide the same function.
By creating a significant amount of construction drawings and details on-site, we avoided any cold bridging and created extremely airtight homes. We maintained a great relationship throughout delivery with the contractor, which ensured that the execution of our designs was meticulous.
Offsetting the Passivhaus over the scheme’s lifecycle
The extra capital cost incurred by designing homes to achieve Passivhaus accreditation had the potential to be offset by lower running costs. This uplift included enhanced triple glazing, more insulation, heavier gauge membranes and additional care during construction to achieve the required airtightness. By minimising fuel poverty and providing homes with lower running costs, the residents of Cameron Close are happier and in their homes for longer, reducing voids for Southern Housing Group.
estimated energy bill savings
estimated for the entire scheme
period estimated for the capital cost
lower than average
gas consumption in 2015
An exacting, meticulous and fabric-first approach to construction
Homes are constructed using H+H’s Thin-Joint system, which combines aircrete blocks with Celfix Thin-Joint mortar. By working closely with the manufacturer we were able to proactively eliminate any issues as they arose. At the time of project planning, aircrete blocks were in short supply but due to our close relationship with the manufacturer, we were able to ensure that our project was supplied.
Thin-Joint blockwork enabled walls to be built very quickly to storey height without having to wait the conventional 24 hours for the mortar to set before further loading could be applied.
Celfix Mortar has been designed to replace the traditional sand:cement mortar, starting to set within 10 minutes of application and approaching full design strength in just 1 to 2 hours. This enabled blockwork to be built extremely quickly, and in the case of cavity wall construction independently of the outer leaf, which is normally brickwork.
Retrofit joist hangers
Another innovative aspect was the use of retrofit joist hangers for the internal floors. This avoided the need to cut blocks or penetrate the walls and removed any concerns with regard to air tightness performance and sound transfer.
By using the Thin-Joint system we could achieve a better-quality construction of the structure enables faster. This allowed follow-on trades to start work sooner in a weatherproof environment, whilst retaining the flexibility of on-site construction.
A key part of Passivhaus design is air tightness. The contractor took a very hands-on approach, with two band saws kept on-site, to ensure the blocks were cut millimetre perfect, before being laid. By minimising the gaps between blocks to the mm we achieved the greatest possible levels of airtightness.
Consideration has had to be given to floor and roof details, for example, to avoid cold bridging.
Newport, Isle of Wight, PO30 5BF
Southern Housing Group
Ground Floor - 0.1W/m2K
Roof - 0.8W/m2K
Ext. wall (houses) - 0.8W/m2K
Ext. wall (apartments) - 0.11W/m2K
Windows - 0.96W/m2K
16 family houses
12 sheltered housing apartments
Housing Design Awards 2016
Housing Innovation Awards 2017
Shortlisted - Most Innovative Affordable Housing Scheme
This highly environmentally conscious development, consists of 26, 100% affordable family homes, all of which meet the Passivhaus standard.
Part of the significant regeneration plan of South Acton Estate, bringing a collection of local neighbourhoods that encourage connectivity between residents.
Our four-phased masterplan, is an impressive development of 126 new and refurbished homes, designed to nurture the diverse community it is set in.