Sustainable Building Guide - Christchurch City Council

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Site Design There are many legal planning requirements and good urban design practices to consider such as conforming to appropriate road boundary setbacks, complying with recession planes, responding to the physical and/or historical context, including shading and landscape, etc. Together with these, try to include suitable orientation for passive solar heating potential and consider roof orientation for active solar devices, for example water heating or preheating. See also topography below for site design guidance. Sill Outside High angle summer sun excluded by external shades Plan through alternative window openings Double glazing Inside Thermal break within frame to prevent heat loss by conduction through frames Section through frame of double glazed window Passive Solar Heating One of the simplest ways to improve environmental performance is to orientate the building towards the sun. The basic elements of a passive solar system consist of a solar collector and a heat storage device (typically a material of high thermal mass such as concrete). The solar collector can simply be the windows and glazed doors of the building carefully positioned for maximum sunlight penetration when it is needed most, on winter days. Small scale design features such as splayed edges to any recessed windows will increase the sunlight entering the building (see diagram opposite). Once the sun’s rays are within the building they are absorbed by objects which are heated up and these in turn heat the air within the space. The heat will be lost through the building perimeter unless this is prevented through thermal insulation and tight ventilation control. Double glazing has an insulating layer of air or inert gas (eg argon) in between the panes of glass to reduce heat loss. Thermal breaks in the frames of double glazing enhance its performance and reduce condensation and mould growth on the interior face of the frame (see diagram). With residential passive solar heating schemes there is the desire to utilise surplus heat gained by the collector during sunny periods of the day for heating during the night-time and cloudy weather. To do this there is the need for some form of storage medium to hold the heat energy until it is required. The storage of surplus heat will also limit and control the potential for the building to overheat during periods of intense sunlight and to cool down excessively at night. In well thought out designs the storage medium takes the form of thermal mass already incorporated in the structure of the building, for example in concrete floors and walls. By utilising the structure in this way there is minimal additional cost for the thermal mass. Low angle winter sunshine admitted to interior
Even with large amounts of thermal mass, spring, autumn and summer over heating is a potential problem and must be prevented. This can be achieved through the use of appropriately sized and angled solar shades, preferably external for increased effectiveness. Ventilation is also essential; at high level, to allow rising warm air to escape and at low level to allow cooler fresh external air to enter. To insure against low levels of solar gain during long periods of adverse weather conditions, you should include a renewable energy source as a supplementary and back up source of heating. Recently designed wood burners, operated correctly, have low particulate emissions and use a renewable, local fuel source. Active Solar In contrast to passive solar design ‘active’ solar devices are usually separate pieces of technology with a single function such as to utilise solar radiation to produce hot water. They can be bought as separate items and can also be retrofitted to an existing building. They may require an electricity supply to power pumps, valves and other controlling mechanisms. The orientation of the roof to the sun will need to be considered if these items are to be easily roof mounted to gain maximum sunlight exposure. Insulation and Energy Use Insist on high levels of thermal insulation in all walls, ceilings and under floors. Thermally line curtains and draught strip around door and window openings. This will allow you to achieve controlled ventilation through purposefully designed vents. Avoid using clothes dryers and other high power usage appliances wherever possible. Select new appliances based on the star energy rating system, the higher the rating the more efficient the product. Use low energy compact fluorescent light fittings and switch off all electrical appliances when not in use. North facing glazing as collector Thermal mass for heat storage insulated from ground below Fan to assist heat dispersal Thermal insulation to retain heat (e.g. thermally lined curtains)
Page 2 and 3: Cover photo credits: Roger Buck & A
Page 6 and 7: Warm air out Materials Try to use m
Page 8 and 9: Design for Change Try to design so
Page 10 and 11: Summer shadows In areas with high w

Sustainable Building Guide - Christchurch City Council

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