A pioneering project by housing association Hanover (Scotland) to provide 15 Passivhaus social homes near Loch Lomond, on the site of the developer ’s first ever scheme, has been given the go -ahead. Jack Wooler speaks to the people behind the project.
Set to be the housing association’s first social housing development certified to Passivhaus standards, Hanover (Scotland) has received planning approval from Loch Lomond & The Trossachs National Park for 15 ‘general need’ homes in the village of Drymen.
The development will replace the original housing which was the first development that Hanover owned when it became independent in 1979 – 18 one bedroom – one and two person – cottages. The buildings have since been demolished with a goal of meeting new sustainability standards, and the existing residents will move into the new development once completed.
The new homes will feature a mixture of terraced bungalows for returning residents, and two-storey semi-detached dwellings. Their Passivhaus design features and benefits include “optimal solar orientation,” as well as thermal comfort, excellent indoor air quality, but also wildflower meadow grass areas for increased biodiversity.
Among the first social housing developments in the country set to achieve the stringent environmental standard, the air-tight buildings will use “vastly less” energy for heating and cooling, complemented by MHVR technology, says the developer.
GOING GREEN
Hanover (Scotland) Housing Association is one of Scotland’s largest housing providers for older people, with a portfolio of more than 5,000 properties located in over 200 developments.
Originally part of Hanover England, the company became an independent housing provider in 1979, its aim being to “promote safe, secure and above all, independent living for its customers through modern and affordable housing,” says Julie McKinnon, projects manager at the housing association.
According to Julie, the decision to demolish Hanover (Scotland)’s original development was based on the advent of more stringent legislation for energy efficiency: “The properties were not meeting the new Energy Efficiency Standards for Social Housing (EESSH), and further improvements to EESSH targets would have been difficult to meet. Daily running costs for the electric heating systems was also proving to be very expensive for our customers.”
As such, Hanover commissioned a feasibility study and it “soon became clear” that the most sustainable option was to demolish and rebuild the development with a new, lowenergy design.
SITE
The development site lies between Conic Way and Montrose Way, to the north-west of the village centre. Its topography slopes from front to back, such that many of the previous homes had stepped access (or access ramps) and, in places, a retaining wall between themselves and the street.
The new development, designed by ECD Architects, ‘regraded’ the site’s levels, moving the retaining wall to behind the properties to create a separation from north to south, and provide the new homes level access from the street.
On Montrose Way, a terrace of onebedroom bungalows provides ‘amenity housing’ which will be offered to returning tenants. At the end of Conic Way and Montrose Way, the units proposed step up to two storeys, to provide greater diversity in the housing mix. The remaining units are twobedroom (three-person) and two-bedroom (four-person) ‘general needs’ housing.
“The new homes have been arranged to step in and out from the street line, which is in keeping with the uneven building line of the street, and reflects the plan form of the former properties on the site,” says Jennifer Rooney, project architect.
Small trees and shrubs have been proposed to the front of the units to enhance biodiversity, create ‘defensible space’ between the street and the housing, and generally enhance the spatial quality and visual aesthetic of the development.
PASSIVHAUS
Hanover looked at the Passivhaus design philosophy for Drymen at a very early stage in the planning process, according to Julie. “The idea was to reduce the impact on the natural environment, and most importantly to reduce the running costs as much as possible for our customers,” she says.
Jennifer explains further: “Buildings built to Passivhaus standards use up to 90 per cent less energy for heating and cooling, and up to 70 per cent less energy than conventional buildings, and have therefore been identified as a key strategy for tackling fuel poverty.” She adds: “They also future-proof occupants from increasing unexpected weather patterns.”
To achieve the Passivhaus standard, the fabric of the new homes is highly insulated and airtight, to minimise home heat losses and reduce energy consumption. All windows have been designed to maximise capacity for natural ventilation, whilst ensuring safety and security are not compromised. Many of the homes have an open plan layout in the living areas, which allows for cross ventilation.
One of the key features of the design is the units’ optimised solar orientation; the two-storey detached properties have been designed with entrance doors to the side of the property, allowing a standard plan form to be used regardless of whether the front is north- or south-facing. As such all of the homes within the development are oriented to maximise solar gains.
The new homes have also been provided with MVHR (Mechanical Ventilation with Heat Recovery) systems to ensure that high levels of internal air quality are achieved throughout the year (particularly during winter when windows are typically closed). MVHR also reduces heat losses by extracting heat from stale air to preheat fresh air.
Solar panels have been integrated onto south-facing roofs to provide domestic hot water to the properties, and air source heat pumps have been located to the rear of properties to provide heating in a sustainable way.
CONSTRUCTION
Hanover (Scotland) is working with experienced partners to achieve these high environmental goals, including Cruden Building, ECD Architects and TCS Construction Consultants.
The project will take approximately 1 year to complete from site start to final handovers and surfacing, and initial aspects will focus on site clearance and the diversion of any existing water main.
The foundation solution planned is ‘trenchfill,’ with an in situ concrete ground floor slab, a highly insulated roof, wall and floor cassettes will form the timber frame, and the external walls will be a mixture of facing brick, render and cladding.
The total cost of this rebuild is expected to be £2.89m. This has partly been funded by a Housing Grant from the Scottish Government, worth £1.26m. The remaining costs are covered by a private loan from the Royal Bank of Scotland (RBS), worth £1.63m.
AGAINST FUEL POVERTY
Considering the team’s approach to the new homes, Jennifer believes that by adopting the Passivhaus standard, the developers are ensuring that they are protecting residents from rising fuel costs. “In particular,” she says, it’s great to know that the amenity houses will be offered up to returning residents who previously lived at this address.”
The residents will be returning to a brand-new house, designed specifically as amenity housing, and with very low energy bills yet excellent levels of thermal comfort. According to Julie, these aspects have led to a lot of positive feedback so far. The project team continues to work with the Drymen community, and says the reaction from its clients has been very positive.
In order to maintain this relationship, a short newsletter is published internally to keep customers and the general public informed about the progress of the project.
“Customers who were decanted at the start of the demolition programme have already expressed their enthusiasm to return to the development at the earliest opportunity,” says Julie.
Looking at the future of the project, the project architect concludes: “We are optimistic about the success of the project, and we anticipate that Passivhaus will set the blueprint for future housebuilding in Scotland, so this an exciting opportunity for everyone involved.”