Built for the Highland Council, the new development comprises two blocks each housing four one bedroom apartments. These have been designed with flexibility in mind to meet requirements for tenants with limited mobility.
The new apartments provide 49m2 gross internal space – approximately 3m2 more than the Council standard for a two person flat. Each apartment is formed from two conjoined modules: one housing the kitchen and living space and the second housing bedroom, shower and utility rooms.
The new homes break new ground in the use of modular building for social housing. The modular system meets many of the key requirements for this sector including speed and accuracy of construction and suitability for building on tight urban sites with minimum disruption to surrounding properties.
Scotland's first modular social and affordable housing is using a highly innovative hybrid system of PEFC certified Cross Laminated Timber, home grown timber and blown wood fibre insulation developed by modular specialists Carbon Dynamic.
The modular system couples rigid wood fibre boards to continuous CLT panels and remains breathable as the uninterrupted layer of CLT also acts as a vapour barrier, whilst preventing the development of thermal bridges. The solid CLT effectively regulates the internal relative humidity and compensates for the lower inertia of the timber construction allowing heat to be stored during the day and released back to the internal spaces as the temperature decreases. Fluctuations in temperature are evened out and relative moisture content is regulated resulting in a healthier environment and increased levels of comfort for occupants.
The flexibility of CLT has allowed for the development of innovative construction details which are ultimately expressed in the finished design and construction processes.
Because of CLT’s stability, it has been possible to completely furnish the modules in the factory including bathrooms, tiling, electrics and even light fittings, before dropping them into position. This meant time on site was dramatically reduced with each of the two blocks of four flats being installed on prepared foundations within two days and services connected within a further seven days.
The apartments exceed the technical standard required for acoustics as well as achieving almost passivhaus standards for airtightness at 0.7m3/m2.h@50Pa. Meeting The Highland Council’s fuel poverty brief, the apartments each have MVHR combined with rooftop photovoltaics and a feed-in providing approximately 1.5 KW at any time, which has resulted an EPC projection for a 3 year energy cost of £723, or £20 per month.
A prototype, fully finished apartment including bathroom, kitchen, carpets, light fittings and furnishings was built in the factory prior to full production so that the client, residents and occupational therapists could spend time ensuring all details were correct before proceeding with the remaining seven apartments.
The apartments are arranged around a central courtyard and each unit has a private outdoor space. The homes will be monitored over the next two years for evolution of temperature between day and night and warm and cold seasons.
BIM has been implemented to its full extent on the project creating attributes that are used for procurement and production. Modularisation requires a great deal of structural design and according to Carbon Dynamic’s specialist timber engineer Max Garcia, this is where BIM comes into its own “The modularisation stage is really important as this is when we input all the information in terms of design, engineering, manufacture and logistics and produce a set of details to be used during the manufacture of the modules.”
“CLT panels are modelled through the BIM platform and sent directly to the CNC machine at Stora Enso which cuts them to size. This ensures accuracy when the product arrives at the factory which means we are able to fit the package together very quickly and be assured that everything is going to work.”
Images: Stora Enso