Buildings need to provide shelter in which their occupants can live, work, play, learn, heal and be fulfilled human beings.
KEEPING OCCUPANTS WARM
Design - Solar heat gain
The best source of heat is the sun. Solar heat gain is maximised by having equator facing windows to catch the low–angled winter sun which heats the interior of the building. Building on an equator-facing slope enhances this effect, as does a building design with a rectangular floor plan which is elongated on an east/west axis. Care should be taken to avoid unwanted shadows from other buildings, trees or the topography.
Design - Thermal mass
Certain building materials such as stone, clay bricks, concrete and rammed earth can retain for relatively long periods of time, heating the structure up and keeping it warm for longer during night time.
Design and construction - Insulation and sealing
Insulation is important for retaining heat. Floors, walls and roof spaces can be insulated to prevent heat loss, in turn requiring less active heating. Glazing can also be specified with insulating properties such as double glazing or film.
Windows and door openings that seal properly keep drafts out and keep warm air in. Green roofs (roofs that have vegetation planted on them) keep the spaces underneath them cool and also tend to cool air that passes over them.
In colder climates active heating is required to maintain the temperature inside the buildings at an acceptable level.
Electrical heaters – electrical bar heaters are the least energy efficient type, while wall panels and radiant (infra-red) heaters are generally much more energy efficient
Wood–fired heaters – open fireplaces are extremely inefficient (5% to 10% efficiency) but slow combustion heaters with an airtight firebox are much better, often achieving 70% efficiency. It is important to ascertain the availability of a sustainable wood supply before choosing this option.
Gas heaters – at over 80% efficiency, this is one of the most effective forms of indoor heating.
Heat Pumps – efficiently use electricity to move heat from one place (the source) to another (the sink).
Central Heating – this will be more efficient when larger buildings are required to be heated.
Users should take care not to leave windows and doors open at times when this will result in the heat inside the building from escaping and in turn require additional active heating. Wearing warmer clothing is much more environmentally friendly than utilising additional active heating. Heating should be restricted to areas in use.
KEEPING OCCUPANTS COOL
The most sustainable way to keep a building cool is to prevent it from over-heating.
Design - shading
Direct sunlight should be avoided. Shading can be created using trees, roof overhangs, dedicated shading devices and screening in front of windows, preventing direct sunlight from entering the building and heating up the space and material inside. East and west facing windows in particular need to be shaded to avoid prolonged exposure to intense sunlight.
Design – ventilation
Passive natural ventilation enhancement, such as having appropriate windows and openings, is the most sustainable way of ensuring ventilation. Air movement is like a circuit and requires balanced and appropriately placed inlet and outflow points to ensure appropriate pressure differentials, which in turn promotes optimum movement through the interior of a building.
Fans promote the movement of air which assists in keeping the interior cool, and can enhance natural ventilation. Air conditioning systems should only be used in well insulated buildings with carefully controlled air flow to ensure that the energy utilised to cool the air is not wasted. There is a wide range of different air conditioning equipment and the more efficient this equipment is, the less energy is used to maintain the necessary temperatures.
Opening the appropriate windows to ensure maximum cross ventilation will help prevent heat build-up. Wearing cooler clothing in hot climates will reduce the need for active cooling while maintaining user comfort. Use appliances like washing machines sparingly and preferably at night. Avoid intensive indoor cooking as much as possible.
PROVIDING GOOD INDOOR ENVIRONMENTAL QUALITY
Introducing fresh air into a building dilutes the concentration of indoor air-pollutants such as carbon dioxide, volatile organic compounds (VOCs), common moulds, bacteria and toxic and irritating chemicals. A lack of fresh air will result in lowered oxygen levels. Combined with high carbon dioxide content, this can lead to drowsiness, lethargy and result in disease and decreased productivity. In extreme cases it may be necessary to filter or purify outside air. Generally, fresh air from outside will be a better quality than stale indoor air.
Excessive moisture inside a building can result in increased levels of moulds and other unwelcome microbiological pollutants. Sufficient ventilation will displace moist indoor air with drier outdoor air. Where outdoor air has a high humidity content, it may be necessary to use refrigeration air-conditioning or dehumidification systems to dry the air. The optimum humidity for the indoor environment is between 40 – 60% relative humidity.
Plants in buildings
During the day, plants consume CO2 and release oxygen, contributing tremendously to improving IAQ. Plants also provide moisture, cool the indoor atmosphere and have been proven to contribute to occupant health and wellbeing. Plants absorb many pollutants and have a soothing effect on occupants.
Unpleasant, harsh or distracting noises impact negatively on both the productivity and wellbeing of occupants. Careful design should be employed, using sound absorbing materials and isolating mechanical noise from heating, ventilation and air-conditioning (HVAC) and other systems and equipment.
The most environmentally friendly way to light the interior of the building is using natural light. Having sufficient windows, and where necessary sky lights, can introduce light into the interior of the building thereby requiring less artificial light which uses energy and heats up the interior of the building unnecessarily. Light shelves are simple structural devices which bounce light into a building and further enhance natural lighting. Light coloured walls, floors and ceilings further reflect light. The design should allow for an even distribution of light while avoiding glare or direct sunlight which can be disturbing.
Energy efficient lighting sources should be specified and utilised. Traditional incandescent light bulbs use a lot of energy and generate significant heat. Some alternatives include:
Compact Flourescent Lamps (CFLs) generally use 50% to 75% less energy than incandescent bulbs, and can last up to ten times longer. They do contain mercury, a toxic metal gas, which is generally not disposed of properly.
Light Emitting Diodes (LEDs) use minimal energy, are extremely durable and give off very little heat. They are currently quite expensive and achieving the required light levels and spread of light can be a challenge, but the technology is developing rapidly. The better quality fittings have built in heat sinks which help avoid heat build-up.
The design of light fittings should include reflective surfaces which amplify the light generated. The ability to switch lights on in smaller zones, instead of the whole floor, is imperative.
The habit to adopt is simple but very effective - switch off all lights that are not required. Use the smallest, most economical light that you can to achieve the lighting levels that you need.
PROVIDING AND MANAGING WATER
Reducing the flow rates on taps and showers will significantly reduce water consumption while generally still fulfilling performance requirements. Excessive water is often used for flushing and dual flush toilet systems can ensure that the appropriate amount of water gets used to eliminate waste. Low flow and dual flush systems can be retrofitted and should be designed into all new buildings. Appliances such as washing machines and dishwashers should ideally be water efficient and should be used on the most efficient settings. Structures and landscaping should be designed to require the minimal amount of water intensive cleaning.
Gardens should be designed and developed to be as water efficient as possible. It is important to plant appropriate plants for the natural conditions. Indigenous plants are generally best suited and seldom require excessive watering. Lawns require a lot of water and lawn area should be reduced. Plants should not be watered excessively and watering should be avoided during hot or windy conditions. Drip irrigation and micro sprays are efficient and avoid excess water loss through evaporation. Soil that is in a good condition and well maintained gardens require less watering.
Rainwater is a ready supply of free water and storage systems such as tanks are relatively inexpensive. Harvesting rainwater also takes the strain off urban stormwater systems, enhancing overall ecosystem functionality.
Grey Water Treatment
Grey water is made up of bath, shower, sink and washing machine water. Kitchen water is generally considered to contain too much fat to be classified as grey water. The residues in grey water such as soaps and detergents are generally relatively diluted and can, in many conditions, be effectively used to water gardens. The use of environmentally friendly biodegradable cleaning products will further improve the usability of grey water. The use of grey water will result in less fresh water needing to be used for irrigation and also decreases the load on the centralised sewer systems by reducing the amount of non-essential waste-water that needs to be processed. It is advisable to get expert advice when planning a grey-water system.
Storm Water Run Off
The built environment creates many hard impermeable surfaces (roofs, paving, roads and driveways). Not only does this prevent the water from sinking into the earth but it also causes this water to flow more quickly than it would in nature. This fast moving water can have a strong erosive effect and urban storm water management is increasingly becoming an issue to be dealt with. Reducing paved areas, green roofs, planting trees and rainwater harvesting are all ways in which the destructive effects of excessive run off can be mitigated. Improving the quality of your soil with additional organic matter can also reduce run off and promote absorption of water.
Water heating, when achieved through electrical resistance heating (as with traditional electric geysers), uses a considerable amount of energy and is one of the major sources of energy consumption in residential buildings.
Heat pumps use energy far more efficiently to heat water. Solar water heaters are extremely effective in using sunlight to heat water.
The processing of sewerage is often energy intensive, complicated and requires a lot of expertise and infrastructure. There is scope for individual building or groupings of buildings to treat sewerage (also known as “blackwater”). Composting toilets, anaerobic digestors, reed-bed and wetland water treatment systems and specialized blackwater treatment systems are all used with success around the world.
Blackwater is effectively toxic and can cause health problems and environmental damage. It is important to consult an expert and the local health authorities before embarking on any process to attempt to treat blackwater.
Kitchens can be busy areas which generally see a steady stream of food, products and waste moving in and out. They also often require a relatively large amount of energy and water for preparation, cleaning and cooking. Locating a kitchen correctly to minimise the transportation of food, products and waste can have a big impact on energy and general efficiency over the lifespan of the kitchen.
The actual layout of the kitchen is important. There is a lot of equipment that gets used and the process of preparing food can be quite labour intensive. Good ergonomics allow for ease of use and enhance the wellbeing of users.
Kitchens face an enormous challenge with remaining clean as much organic waste is generated by food preparation and consumption. The kitchen should therefore be easy to clean, at the same time minimizing the use of fresh water and detergents.
Cooking generates a lot of heat and well ventilated kitchens will ensure that this heat is not transferred to other parts of the house in warm conditions. Additionally, pleasant cooking aromas become unpleasant odours over time and ventilation will keep the air fresh.
Appliances and equipment are used extensively in kitchens. Gas is generally far more efficient than electricity for cooking. Where electrical appliances do need to be used, care should be taken to ensure that these are as energy efficient as possible. Water efficiency can be enhanced by using low flow fixtures and water efficient dishwashing equipment.
Food security is increasingly becoming a challenge due to climate change, global economic instability, environmental degradation and excessive use of chemicals and genetic intervention. In addition, transportation is traditionally not very environmentally friendly. A kitchen that requires its produce to be transported over a long distance has a far higher carbon footprint than one which uses locally sourced produce.
Buildings create fantastic environments in and around which food can be grown. Waste water is often well suited for irrigation and buildings themselves effectively create topography which can be used to create microclimates and enhance productivity. Kitchens generate waste which is turned into compost and which in turn is a source of nutrients for vegetable growing.
Fewer products being brought into buildings will mean less waste when those products are used up or replaced. Packaging generates enormous waste and attempts can be made to minimise this. Unfortunately many products are manufactured with built-in obsolescence. Purchasing higher quality products, or those that can be repaired, will assist in minimising the disposal of broken or worn out products.
Separation and Recycling
Recycling eliminates waste output. Paper, glass, metal, plastic and organic material can all be recycled. For this to happen effectively, the building design and usage procedures should be conducive to easy separation of the different components of waste so that recycling can take place efficiently and with the least additional input. The separated items need to be transported to various processing destinations and the transport and movement of waste should be considered in the design process. However city waste management systems are increasingly taking care of this.
There is a growing collection of building materials that are produced from recycled waste. Obviously these have an overall positive impact on the environment since they are both removing waste and reducing the demand for natural resources. In addition many building materials can be reused with minimal reconditioning.
Organic waste can be used to make compost which not only disposes of the waste effectively but also is a rich source of free nutrients for food and ornamental gardens. It is possible to get small, efficient composting systems that allow for composting to take place in urban areas. Worm farms also allow for the conversion of organic waste into plant nutrient substances and can be very compact, neat and convenient.