The adverse affect that our buildings have on climate change has been well documented over recent years. Over 40% of the UK's carbon dioxide emissions come from the energy we use to heat, light and run our buildings. While there have been many proposed solutions to the problem, most of which have tended to focus on how we design our homes, as an industry we still seem undecided on which provides the best long term solution to the problem. The imminent changes to the building standards will push the industry towards achieving the recommendations of the Code for Sustainable Homes in England and Wales and the Low Carbon Building Standards Strategy for Scotland (' the Sullivan Report'), with the agreed starting point being increasing thermal insulation and air tightness. Most accept that this is achievable within the realms of developer house building. But the full zero carbon ambition ( or net zero carbon as it more likely will be) may not be readily achievable without expensive renewable add- ons, which are likely to be cost prohibitivefor the mass market housing industry. Here, following on from Steff Bell's articles in the previous two issues of AT, weaim to fuel some further discussion on the low carbon housing strategy and look at how we might learn from Germany, adapting their standards to the Scottish climate. We hope our work on the Passive House project at Scotland's Housing Expo, in Inverness in August, might inform or even inspire the industry towards a workable and realistic solution for future low energy housing. Scotland's Housing Expo Scotland's Housing Expo will be a unique event in the UK, based upon similar models found in mainland Europe, particularly Finland, where historically the housing fair concept has proven very successful in stimulating quality design and innovation in Finnish housing. The Expo aspires to be a catalyst for prompting a similar kind of change within the Highlands and throughout the UK. The Expo itself will showcase over 50 architect- designed houses, featuring innovative construction and cutting edge sustainable systems plus the very latest in product design, landscaping and interiors. A programme of events throughout the month of August will appeal to industry professionals and visitors to the site. The homes, which have a strong focus upon high quality design, innovative technology and the use of sustainable systems and features, will be available for sale on the open market with 40% available for rent through two local housing associations after the event. By creating an exemplar communityin line with a fantastic masterplan by Johnny Caddell at Caddell2, the Expo will act as a model for future housing design and development. The legacy of the Expo will be a living, breathing, contemporary village which hopes to significantly influence the standards of housing in Scotland and the UK in years to come. For more information on the event see: www. ScotlandsHousingExpo. com. ATJULY- AUGUST2010 19 A Scottish Passive House The Passive House concept is explained by Jim Lindsay TCIAT and Ross Barrett, both of HLM Architects. The Expo will act as a model for future housing design and development PASSIVEHOUSE Right: competition sketch - rear garden elevation Far right: competition sketch - front elevation

HLM Architects designed the competition winning scheme for Plots 11/ 12 within the masterplan and are working with O'Brien Properties and Buro HappoldEngineers to deliver the units ahead of the event. The Scottish Passive House Centre ( SPHC) also played a key role in the project, supporting the design team through the detail design stages with energy efficiency consultancy and Passive House Planning Package ( PHPP) Calculations. The SPHC will also carry out the air pressure testing to confirm the buildings as some of the most air- tight in the UK and will supply vital Passive House components for the construction of the units including the MVHR System and Triple Glazed Passive House Certified Windows. Passive Journey Our Passive House journey began in early 2007 when presented with the opportunity to look at the Highland Housing Fair competition ( as it was then known). The competition, organised by the RIAS and initiated by The Highland Council and the Highland Housing Alliance, set out to look for innovative, low energy housing which would look to raise the bar for Scottish and UK housing. The competition gave our practice the opportunity to continue our exploration of a low energy approach to our buildings and, in the context of previous work we had done on the Inverurie sustainable housing competition and a number of larger built projects, we embarked upon an investigation of European approaches to low energy housing design. Eventually, we looked towards the model of the Passive House, which refers to the rigorous standard for energy efficiency in buildings pioneered in Germany in the 1990s. Translated to Scottish Housing, it results in ultra low- energy buildings, dispensing with conventional heating systems altogether. Passive House Design Taking the competition zone theme of solar design, our terrace exploits the climate and in particular solar energy to significantly reduce energy consumption as part of the Passive Housephilosophy. The main living spaces are orientated to the southern climate- inclusive side of the house using the elements and climate to reduce reliance on energy; the utility spaces to the north inhabit what appears to be a thick, heavily insulated north wall - excluding the cold climate and closing out the elements. Small openings are provided in the north wall creating the effect of a quiet demeanour to North Street while minimising overlooking. The rear of the house, however, is intended to be much more private and, in a sense, more dramatic and is therefore treated with a more modern approach. Large expanses of south facing glazing help to create an open feeling towards the garden and to the woodland and trees beyond. At night the glazed living spaces can glow beacon - like into the dark reaches of the garden. HLM's terrace is one of the first Passive House Schemes in the UK, and will achieve an 80% reduction in energy consumption ( heating, domestic hot water ( DHW) and electricity). A typical three bedroom new build in Scotland of similar floor area would consume approximately 15,000 kWh/ a for heating energy. The heating demand estimated for our Passive House is 1,430kWh/ a ( less than 1/ 10th of a conventional new build house). The maximum power output for the heating has also been calculated at 9W/ m2 ( or 963W for the whole house), just below the maximum Passive House threshold of 10 W/ m2. The household appliances and occupants of the house will produce enough heat to cover this demand - with one person producing 60- 100w heat. We also calculated that a hairdryer could heat the house on a cold day! This achievement is made possible by careful orientation, shape and a compact form taking full advantage of the climate and solar gains and using a closed panel timber frame system to achieve a Super Insulated Building Fabric with the U- Values for walls, roof and floor of 0.1 W/ m ² K and windows a U- Value of 0.71W/ m ² K. The following gives a more detailed look at how we created a building envelope to meet 20 ATJULY- AUGUST2010 PASSIVEHOUSE Left: proposed interior