Renewables and other, new, innovative products often grab the headlines in our industry, and it is recognised that this innovation is key in ensuring new technologies are pushed to market and start to replace the older, inefficient products still widely used in our building stock. However, our consultants reinforce that, in reality, low energy design principles are crucial.
One of the main fundamental principles of sustainable homes design, alongside meeting compliance with Building Regulations, is to work with nature, rather than against it. In practical terms, this means harnessing power from the sun, wind and ground to heat houses in summer months and cool in winter months. How can this be done? Our experienced consultants have provided some expert advice below.
Location and Positioning:
Careful positioning of the building creates a balance between the passive solar gains from the glazing, screening/shading to reduce overheating and maintain consistent temperatures, and ensuring sufficient levels of insulation and airtightness. If possible, the majority of your glazing should be south facing, which then creates potential to build a ‘passive solar house’, which utilises the energy from the sun to provide the majority of the space heating requirements. In contract, north facing envelopes should have less glazing and maximum insulation.
Managing over glazing/ overheating:
Where houses are designed to be super- insulated, the approach to orientation is different, and heat requirement may be so low that cooling becomes the biggest consideration, and as such, over glazing the south facing envelope should be avoided. Where views need to be maximised on the south facing envelope, overheating can be minimised by screening out light. For summer overhead sun screening, a small roof overhang and brise soleil (horizontal slats positioned over the window) may be ideal. For lower, winter sun, or east/ west facing windows, where light can be harder to screen out, planting, blinds, or shutters may be more appropriate.
The glass and mass approach:
Although a beneficial source of energy gain throughout the day, even the most thermally efficient glazing is a main source of heat loss at night. If you consider that even the best performing windows will only achieve a U value of 1.0 W/m²/k, whereas the maximum U – value limit for a wall, under current building regulations, is 0.35 W/m²/k, any break in main fabric mass will create heat loss. Passive solar design overcomes this by incorporating a high level of thermal mass within the building – solid concrete floors, and walls using concrete blocks, stone or brick. These materials create thermal mass capable of keeping houses cool during the day and warm at night. Subsequently, buildings with high mass tend to benefit from low – temperature heating systems such as underfloor heating.
Working outwards to inwards:
Creating a comfortable environment can be costly, consistently warming/ cooling to optimum temperatures. Therefore, designing rooms requiring little/ no heat in the north/ east/ west, and those requiring heat to the south/ centre is a more inexpensive and beneficial approach.
Ventilation is crucial:
For those air tight homes, ventilation is crucial to avoiding damp conditions. The low – tech approaches include natural ventilation (utilising openings such as windows and doors), and passive ventilation – harnessing the principle that through convection, warm air rises to remove stale/ damp air controlled through humidity ducts. Mechanical ventilation, despite being the most expensive to install, is still currently the most effective and consistent approach.
Working with one of our technical energy consultants will give you access to industry leading advice, which is individually tailored to each property designed, enabling you to maximise efficiency, including sustainable features that not only meet and exceed current regulations but will also continue to work in the future as the climate changes, and also running costs and expenditure on energy to a minimum.
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