ENERGY EFFICIENCY AND SUSTAINABILITY

Living in our current environment demands that energy be used sparingly in the full life cycle of a building.

Energy consumed for the manufacture of materials and during the construction process of a building.
The daily energy consumption by a building to fulfil its functional expectations and maintenance required during its lifetime.
Energy required to demolish and process the remains of a building in a responsible manner at the end of its lifecycle.

The same principal applies to the conservation of natural resources when planning the design and construction of buildings. The use of properly managed sustainable materials must receive preference.

The following factors, which play an integral part in the conservation of energy and resources in a building, must be addressed as part of our lifestyle.

ALTERNATIVE ENERGY SUPPLY

A system, comprising of photo cell panels, a battery storage unit, and an inverter, can make a difference to the energy consumption of any building. A full range of systems are available to suit different needs and capacities and most of these systems are extendable. If power efficient lights are installed throughout a building, a basic system that can provide adequate power for all lighting should be an affordable option.

Gas should be considered as an alternative energy source for cooking and is also more energy efficient for water heating than electricity.

SPACE HEATING AND COOLING

Electrical radiant heaters, wall panel heaters, oil radiator heaters and underfloor heating consume a lot of power. Gas is more efficient to produce the same heat. There are also a range of open or closed solid fuel (wood or coal) burning options available to suit different needs.

The use of air conditioning units to cool down spaces should be considered carefully. The first design consideration should be to limit excessive solar heat gain to the building. Orientation and shading of large windows and proper insulation of exposed facades must be addressed in the design.

When air conditioning is an essential design requirement, only environmentally friendly systems with energy efficient pumps, should be considered.

WATER HEATING

Conventional hot water cylinders using an electrical element (electrical resistance heating) consume a lot of power (up to 60% of the annual power consumed in a household). SANS 204:2011 – STANDARDS FOR ENERGY EFFICIENCY IN BUILDINGS prescribes that a minimum of 50% of the annual average water heating in a building shall be provided by means other than electrical resistance heating.

Solar heating is very efficient and probably the most popular used system but adequate storage capacity, for the hot water, must be provided – they don’t heat the water at night or during cloudy days.
Heat pumps are very efficient in transferring heat from the outside air to the water in the hot water cylinder. This is done by means of a refrigerant that absorbs the available heat from the outside air through an evaporator. The refrigerant is then further compressed (which further raises its temperature), before it is pumped through the hot water cylinder where it gives off its heat to the water. The only electricity consumed is by the pump and a fan circulating the outside air through the evaporator. A heat pump uses approximately 25% of the electricity of a conventional electrical element to produce the same amount of heat to the water. Make sure to specify environmentally friendly systems with energy efficient pumps.
Gas water heaters have become very efficient and relatively maintenance free. Different systems for different applications are available. Gas can warm water up instantly, should that be required.
Hybrid installations are becoming more popular – combining the best attributes of different systems. One such installation consist of a solar system which pre-heat the water to 35˚C before it is stored in isolated cylinders. Gas water heaters is then used to heat the water further to 55 ˚C on demand. This reduces the gas consumption drastically.
All warm water pipes must be isolated to prevent heat loss.

INSULATION

Proper insulation of the external envelope of a building is essential to conserve energy consumption of a building.
Standards for the thermal performance of materials and components making up the envelope of a building are prescribed in SANS 204:2011 – STANDARDS FOR ENERGY EFFICIENCY IN BUILDINGS and must be incorporated in the design of a new buildings.
On existing buildings air leakage through the roof, door and window assemblies are responsible for a lot of heat loss. This can normally be addressed without major disruption. Improved roof insulation is one of the most cost efficient ways to improve the thermal performance of a building. Replacing of windows frames or re-glazing of existing windows can influence the thermal performance of a building drastically and can reduce installation and running costs on air conditioning. Window specialist can retro-fit aluminium or timber frames over existing window frames without removing the existing frames.

WATER CONSUMPTION

Water conservation has become an important consideration in our current environment.
Due to the inconsistent fresh water supply in some areas, the installation of a fresh water storage facility for a building has become a necessity.
The collection and storage of rain water from roofs and paved areas should be considered in the design and construction of a building. A range of rainwater harvesting solutions and storage tanks are available.
On site filtration and recycling of water for garden irrigation or flushing of toilets has become possible, as more on-site sanitation solutions and storage tanks are available on the market.