Set in the hamlet of Gorstan in the Scottish Highlands, Tigh-na-Croit, a fully certified PassivHaus, nestles quietly into an area of former crofting land to the north of Hillcrest Cottage and west of Hill Cottage.

The brief was simply to create a quality modern and low energy PassivHaus from which our clients could continue to enjoy their love of outdoor pursuits whilst living in an environmentally responsible, low impact home.

Design Approach

We proposed a contemporary architectural solution where the scale, proportion, openings, roof pitch and mix of materials are all contextually relevant to the rural landscape.

Given the rural context, the design concept took inspiration from the form of a traditional steading in creating an appropriate scale and form for the site. The house has been designed specifically for the site and demonstrates confidence, articulation and design quality to create a high quality, low energy design looking towards new successful precedents of rural, Highland Housing.

The house comprises generous living space, kitchen and dining room, 3 bedrooms, utility space, cinema room, sanitary, utility and storage space. The living areas face south making the most of views with a small terrace allowing the client to enjoy the beauty of the surrounding landscape. The bedrooms are then orientated eastwards to capture morning sun. Oversized windows allow internal spaces to connect visually with the landscape and take advantage of the many wonderful views from the site.

Given the setting, the importance of sustainability, and rural context, the design utilises of a mix of materials including rendered walls, locally sourced timber cladding and slate roof. The primary material for the house is white render with limited areas of stained timber cladding used at the dining room ‘box’ on the south elevation and small areas to the north and west elevations. Glass also features heavily, allowing the framing of particular views and maximising the potential of passive solar gains as part of the passive house design philosophy. Recognisable details of highland rural forms are used in terms of chimneys, roof pitch, verges, eaves and carefully placed openings. All of this succeeds in maintaining a sense of place and supporting local identity.

Energy
The dwelling adopts the European ‘PassivHaus’ philosophy for energy efficiency which results in an ultra low-energy house dispensing with a conventional heating system altogether. Through careful orientation, a compact simple form, high levels of air tightness and a super insulated building fabric the design reduces energy consumption by 80% whilst ensuring excellent internal comfort conditions throughout the year. A balanced mechanical ventilation system with heat recovery is also employed as a key element of the strategy, reducing heating bills and providing cleaner, fresher excellent quality of indoor air. Hot water is then provided from regenerative sources via heat pump with provision for a future solar thermal system.

As one of the most northerly certified PassivHaus projects in the UK, Tigh na Croit achieves an 80% reduction in energy through considered orientation, simple architectural form, careful detailing, high levels of air tightness and a super insulated building fabric.

An off-site prefabricated closed panel system was utilised for wall, floor and roof elements, which along with high performance windows provides a super insulated air–tight building fabric (U-Values of 0.1W/m2k and an air tightness 10 times better than building regulations).

The panels utilise predominantly home-grown timber and contain a locally manufactured insulated core of high recycled content glass wool insulation. The entire project makes a positive contribution to the local Highland Economy by ensuring a high proportion of local labour, local materials and local manufacturing expertise was utilised.

Through careful detailing, the fabric massively reduces ventilation heat losses whilst ensuring excellent thermal comfort internally. A balanced mechanical ventilation system with heat recovery is also employed as a key element of the strategy, reducing heating bills but also providing cleaner, fresher excellent quality of indoor air. Domestic Hot water is then provided from regenerative sources via an air source heat pump with provision for a future solar thermal system. Over 98% of installed light fittings are then low energy.

Water consumption is considered through the specification of low flush WCs, reduced flow rate taps and showers and provision of localised water butts for rainwater recycling.

According to PHPP calculations the annual heating demand has been calculated at 15 kWh /(m2a ) and through rigorous modelling and calculations based on built European PassivHaus, it is estimated that the house will cost little more than £100 a year to heat.