Initial situation: The existing building was a former nursing home and was incapable of adaptive reuse; however the materials were re-used when possible.
Description: The requisites of the SNH were to incorporate open plan offices, meeting rooms, a publicly accessible boardroom and library together with staff facilities; including staff room, gym, changing rooms and workshops. More importantly, the design of the new building had to reflect the culture of SNH as defined in their 'Corporate Strategy, a Natural Perspective' and how SNH wished to project itself to its partners, staff, customers and the wider public.
A key feature of the ethos of SNH is that resources must be used responsibly and sustainably. This, therefore, entailed the need for low operational energy, removing waste from the construction process and represent value for money in both capital and running costs.
Construction started in April 2005 and was completed in June 2006.
A linear atrium was built at the heart of the building. The offices, library, meeting rooms and boardroom are all arranged around it which maximises visual connectivity. The atrium not only serves as the primary entrance but also as the driver of the natural ventilation. The design of the atrium allows the air flow to circulate and also allows the air management in the offices surrounding it. Within the Atrium two bridges provide access between the west wings and the offices and an open stair provides access from Atrium floor.
Views out across grand landscapes are everywhere. Timber is dominant internally and externally and the overall impression is light and spacious. The health and wellbeing of the building occupants were both considered an important objective therefore, it was decided to work towards a less commercial feel for the workplace character. Staff eating spaces enjoy sun and landscape both inside and out.
Materials, components and systems were ‘A’ rated according to the “BRE Green Guide to Specification”. Much of the existing building’s materials were recycled on site into the new building. It is highly insulated and airtight, with natural ventilation using the offices’ exposed concrete thermal mass for cooling. Solar power is used to preheat the water. The materials used were generally indigenous to Scotland, and natural and local wherever possible.
Materials recycling and specification of green materials: The masonry was crushed on site and provided 34 % of the high grade aggregates used in the new building. The slates were re-used as cladding on the stair towers. Softwood flooring was redressed on site, and used internally and in external sheltered locations. Items like cast iron radiators; not warranty-capable, were salvaged locally. Local materials were specified where possible, particularly for timber cladding (Scottish Larch), which came from 350 tons of manually selected and locally converted logs from locally managed woodlands. Local main contractor embraced the ‘Considerate Constructors’ scheme and as a result, was one of the highest performers in the UK concerning this scheme. Waste Minimisation called for broad use of standardisation and maximised use of materials minimised waste. Standard timber sections and profiles were developed efficiently into bespoke elements. Timber panels and components were standardised. Predicted water use per occupant was only 0.99 m³ against a best practice target of 6.4 m³. As part of the Considerate Constructors policy, waste was monitored, and the BRE audited waste and environmental management monthly. Waste types were separately recycled and all fuel use recorded.
Landscape: was developed along truly indigenous lines with SNH and Highland Council using species of local provenance from local suppliers. The SUDS pond/wetland introduces new habitats, encouraging flora and fauna proliferation. New heated bat roosts were incorporated.
Energy and Water Efficiency:
Heating is gas-fired as non- fossil fuel energy sources were not able to be established nor the supply reliability confirmed in the given time period of the construction process. The capacity to convert the system to take a contribution from biomass-fuelled boilers or wind energy is incorporated in the building.
Efficient condensing boilers have been used - recycling heat from the flues, operating at a low temperature and being more efficient.
Only the server room is artificially cooled. Offices and meeting rooms are naturally ventilated, driven by passive solar and wind effects. The Office uses the exposed concrete ceiling slab as a daytime heat sink. During cooler night periods, high-level windows open automatically and external air is drawn over the slab. During the day, fresh air is drawn into the atrium through the offices either by manual opening or automatically through BEMS CO2 monitoring. Warm air discharges from the atrium through 4 high level baffle controlled independent solar chimneys. Overall this reduces the predicted (TAS modelling) heating season to only 17 weeks.
40 mm thick Caithness Slate (local material) flooring is used in the atrium. This is laid on the reinforced concrete floor slab, which has hot water pipes in it and 100mm insulation below. The slab acts as heat ballast. In the winter the black floor slabs absorb heat from the atrium sunlight to contribute to the heating and convection process.
Solar collectors provide around 62 % of the hot water needs. The energy rating for power, light and heat is expected to average 76 kilowatt hours per square metre per annum. The electricity usage should average 25 kilowatt hours per square metre per annum, against a benchmark of 54. The building´s carbon emission is 7.16 kg carbon per square metre per annum against a benchmark of 15.
Photovoltaic solar panels were considered for electricity generation. Unfortunately, current technology is such that they are only 16 per cent efficient (according to the European Commission Joint Research Centre <EC JRC> PV Status Report 2011, p. 70) and at the time it was two or three times the cost of energy produced by fossil fuels. The payback period was considered too long and the installation would only have been viable with government grants. The estimated 24 month grants approval cycle precluded this.
A future energy strategy may involve a mixture of solar and wind power. While the former peaks in the summer, the latter peaks in the winter when the demand is greatest. It has been estimated that sufficient wind would be available for about 90 % of the year in Inverness. Current experience suggests that several micro-turbines will be more efficient that one large one.
Lighting has passive infrared sensors which detect a lack of movement and then switch off and automatic adjustments are also made as external daylight varies. The large amount of daylight able to enter the building, with louvres controlling the amount of glare from sunlight, minimise the need for artificial lighting. There are sunpipes in the boardroom to enhance daylight.
The external walls and roof have a thermal insulation level 15 % higher than the Building Regulations minimum standards.
Measures: Benefits/ Results:
- Design and construction were fully monitored by BRE and on completion achieved the highest ever office BREEAM score of 84.01%. Post occupancy evaluation is under way.
- 76.66 kWh/m²/year of energy (power, light and heat)
- 17 m² of evacuated tube solar pre-heat collectors provide 65 to 80 % of hot water needs.
- Overall carbon rating for the building - 7.16kg/m² per annum.
- Envelope U-values exceed Building Regulations by 15 %.
- Air tightness test result - 4.78m³/hr/m² at 50 Pa.
- Rainwater is recycled from the office and atrium roof, via a 6000 litre underground tank, for toilet flushing.
- Heating and hot water use are approximately 50 % of accepted benchmark figures for naturally ventilated buildings.
- The EPI (Environmental performance indicator) score was 10 (maximum).
- Office lighting daylight sensor and PIR controlled
Awards: Since completion Great Glen House has gained many national awards for its design and sustainability credentials, including:
- Sustainability Award - AJ100; Green Apple Sustainability Award 2007; Scottish
- British Council of Offices, Corporate Workplace of the year, Regional (Scotland) and National award, 2006
- Property Awards Green Building of the Year 2007;
- BRE Office Building of the Year for 2006;
- Sustainable Building of the Year 2006 - Building Magazine;
and a Special Mention at Civic Trust Awards 2007; It has also been shortlisted for: The Scottish Design Awards 2007; received a Commendation in the Sustainability Category at the RICS Awards Grand Final 2007 and the Inverness Civic Trust Award 2007.