Some suggestions by Mike Schroeder and Mark Borchers
A sustainable building is not something that requires huge resources or great expertise to develop. With a little knowledge much can be done for no extra initial costs, resulting in a more environmentally friendly and healthier living or working space, and with much lower operating costs. Some choices cost more up-front, but pay for themselves over the life of the building (often many times). As a quick guide, a checklist of eight critical considerations for a sustainable building follows (more detail in later sections):
- Recycle existing old buildings rather than building new ones on more land.
- Use materials that have a lower “embodied energy” – i.e. use less energy in their production. For example, unfired bricks are better than fired, and cement bricks with mostly recycled content are better than conventional cement bricks. Consider compressed earth bricks or cob construction where feasible.
- Design the building with “passive solar” features to keep it cooler in summer and warmer in winter. In houses and offices this will reduce or eliminate the need for air-conditioners (these consume most of an office’s electricity).
- Design to maximize natural lighting – this saves electricity (lighting is a major electricity consumer in homes and offices).
- Use renewable energy where financially feasible – for houses, installing a solar water heater is cost-effective and saves a huge amount of electricity (and money) over the years.
- Choose local contractors and materials where feasible to reduce transport environmental impacts and stimulate the local economy.
- Promote a healthy natural environment around (and in) the building – for example by keeping the paved surfaces to a minimum, and planted areas to a maximum.
- Choose a site which will minimize transport distances for occupants – near where occupants live or work, where people can bicycle or walk to and from the building, or a position well serviced by public transport.
- Also remember that a sustainable building needs to be a physically and mentally healthy place for occupants to spend time.
The notes below discuss some of the practical choices facing those developing a sustainable (“green”) building.
For a more energy efficient building
- Use passive solar design to reduce energy consumption and thus need for extra equipment such as air conditioning, and to ensure comfortable accommodation:
- North orientation to ensure that as many well-used spaces face North as possible. Sun control is more difficult on East and West facing windows. South facing windows can capture good reflected light from the sky elsewhere, but very little solar energy.
- Good insulation in the roof and walls to keep the inside temperature warm in winter and cool in summer.
- Suitable roof overhangs to let in the winter sun but shade from the hot summer sun.
- Sensible fenistration (windows) – let in the light and catch the winter sun, but not too much window area so that warmth or coolth cannot be retained inside when needed. They can be combined with shading and reflecting devices such as overhangs, screens, shutters, awnings, trees, planting, different glass-types, to control the amount, quality and time of daylight entering the building.
- Suitable ventilation for fresh air and coold breezes – and so rooms can be ventilated as suitable using airbricks, opening windows, or forced ventilation.
- Natural lighting through windows and light wells.
- Install solar water heaters: these are relatively expansive but result in substantial savings on your electricity bills (water heating is the biggest part of most households’ electricity use profiles).
- Artificial lighting: if needed, energy efficient light bulbs are usually more expensive than conventional incandescent light, but have a much longer lifespan and use far less electricity. They pay themselves back in a few months and are a very sound environmental choice.
The site: Choosing and making the best use of the site
- Transport and access
- Choose a location that reduces distances between home, work, school and shops to reduce fuel consumption and pollution. Look to the availability of energy-efficient transport, public transport or shared transportation.
- Recycle existing buildings rather than building new ones on more land – this makes the best use of developed land, infrastructure and other resources (recycled buildings often have attractive older features).
Position the building – make best use of sun, shade, wind, outdoor space
- Have as little impact on the site and existing natural systems as possible:
- Avoid major cut and fill, protect useful topsoil, and place the building and paving on those parts of the site least suitable for planting and outdoor activities (too steep, too much rock, sun, wind, etc.)
- Minimize area covered by the buildings, parking, driveways and other paving, and look to green a much of the space around the building as possible to promote natural systems, assist the cooling/heating and outlook of the building, and to provide attractive, useful outdoor spaces.
- Maximise opportunities to capture useful sunlight, rainwater and prevailing winds to assist comfort and health in the buildings, and to provide protection from unwanted sun, wind and rain (damp).
Services and connections
- Choose a site on developed land, with existing infrastructure and buildings if suitable, so that the negative impact of developing all this infrastructure is avoided where possible.
- Provide space for waste recycling, composting, grey-water recycling and rain water collection tanks.
Climate and comfortable, healthy buildings:
- Good information about the local, or micro-climate of a site helps one design a building to best respond to expected conditions (expected daily and seasonal temperatures and humidity, sunlight quantities, direction and angles, wind strengths and directions, rain, storms, hail, air quality and noise).
- Looking at how well other buildings in the area perform will provide useful lessons on what makes good living conditions (and what doesn’t). This information is useful to help decide the position, orientation, and materials of the building.
General sustainable building issues:
- Make sure that the proposed buildings and spaces (rooms) are “right-sized” (avoiding wasted accommodation and energy consumption). The savings can fund improved features, and energy-efficient materials, fittings and performance.
- Use “local” as far as possible: local materials, knowledge and skills will save transport costs, are often matched to local climatic conditions, and help develop/sustain local economies.
- Consider using standard material building sizes where feasible to avoid waste and extra transport to remove waste from the building site.
- Indigenous vegetation and planting is best suited to the local soils and climate. Deciduous trees can help shade buildings in summer and allow sunlight to warm spaces in winter, reducing the need for heating and cooling.
- Be sensible rather than fashionable – avoid using fashionable trends when selecting finishes and other aesthetic choices because these often quickly look tatty and tardy and then one is required to refurbish, Rather ensure finishes and materials that ensure healthy comfortable buildings which can be economically cleaned and maintained.
- Water-saving appliances are becoming generally available – dual-flush toilets, low-flow shower heads and tap aerators are inexpensive and save huge amounts of water over their lifetime.
- Good sealing of doors and windows ensures optimum control of conditions in individual rooms or particular spaces in a building.
- Investigation of energy efficient, non-toxic insulation materials is important, such as treated organic fibre (waste timber) chip, recycled paper, and possibly polyester.
It often makes sense to employ competent professionals familiar with technology and practice for sustainable buildings to save having to upgrade poorly performing buildings and pay extra for heating, lighting, air conditioning, water heating, etc.
Sustainable building materials:
Environmentally-friendly, and energy-efficient construction technology and materials are not widely used or accessible in South Africa, so most South Africans are unfamiliar with these approaches. The market is dominated by conventional technology, which is little concerned with environmental and social impact. That most offices end up more like “batteries” where staff sit in cubicles and “produce” under artificial lighting shows that a pleasant daytime environment and staff welfare is certainly not high on the list in mainstream business thinking.
Select renewable materials which use least embodied energy, and require least transport and produce least pollution and waste. Some innovative alternative technologies are beginning to become better understood in South Africa and should also be investigated: use of plantation timber frames and panels, sand bags in timber frame, soil cement and unfired clay bricks, and cob or straw bale construction.
For most conventional building materials, there is now an environmentally friendly alternative available on the market. Call a sustainable building consultant like The Sustainable Living Centre in Westlake for more information. Their details and link can be found at the end of this article.
Further energy saving options:
Other options for improving energy consumption that are used in “green” buildings include:
- Capturing and storing heat inside the building in “thermal mass” (heavy floors and walls) or flushing buildings during the night to cool the internal structure.
- Forced ventilation can be used to raise or lower uncomfortable humidity, or to blow dry air over water to cool and increase the humidity of the air in very dry areas. Devices designed to ventilate warm dry air over fountains, pools or wet fabric screens, or fine water spray can e used for this. Solar-generated electricity can be used to power fans.
- Solar heated water can supply heat exchange geysers to provide hot water to underfloor heating and certain types of wall-mounted radiators. Also, some buildings have been using warm air from roof spaces to warm cold spaces either directly or via storage in thermal mass (under-floor rock stores).
- Solar electricity – photovoltaic positioned to harvest sunlightgenerate “green” electricity which can reduce use of ESKOM electricity (very dirty energy). Wind generators can also be used to generate electricity on site. The electricity generated on site can be connected to the main supply grid, so if a surplus is generated, you sell it back to the grid.