GreenTips

The most common renewable energy generation systems used in buildings are photovoltaic panels, wind turbines and micro-hydro generation systems. The type of renewable energy generation selected will be dependant on the location of the building and the amount of power required.

Small scale vertical axis wind turbines are now available which have been designed to be effective in the changeable wind environments typical in urban areas.

Advances in photovoltaic technology are rapid, with many options that can be integrated into the outer building fabric. Photovoltaic roofing tiles, membrane and even glazing is now available.

Some external electricity providers are making real efforts to generate power from sustainable resources while others are still heavily dependant on coal. Ask your provider where your power comes from and consider switching if you don’t like the answer.

Traditional PVC cables can contain toxins known as halogens which are slowly released into the air and produce toxic smoke in fires. PVC is considered by many environmental organisations to be a material which should be avoided, though this has recently been debated by some. PVC and halogen free cabling is also available in New Zealand but usually at a cost premium.

Reducing the energy needed for artificial lighting can have a huge effect on our total energy use. Energy required for this in commercial buildings is typically 30% of the total energy use. In domestic buildings it is typically 10%.

Many lighting installations are over designed, with far too many fittings installed for the light levels required. As a general rule a target of 10W/m² installed lighting should be sufficient in most commercial spaces.

Ceiling mounted halogen down lights have recently been associated with a number of fire hazards. If using these, ensure they are professionally installed and that minimal ceiling insulation comes into the radiant heat zone that emerges from the light.

The use of daylight sensors, proximity sensors and timers can all significantly reduce power usage as we are generally much better at tuning lights on than turning them off. Sensors that automatically dim the lights in response to increasing daylight are generally the most effective and cause least irritation to building occupants.

If traditional incandescent lamps are used, 95% of this energy is given off as heat. Compact fluorescent light bulbs can be used as a simple replacement for incandescent bulbs in most domestic situations. They can reduce energy use by up to 75% and last many times longer. Due to their inherent inefficiency there are several international initiatives to phase out the sale and use of incandescent light fittings in Europe, Australia and in the US

New T5 fluorescent lighting fittings with electronic ballasts are a lower energy option than traditional fluorescent lighting in commercial situations.

New advances in the use of LED light fittings have created options for very low energy, very long life and mercury free light sources.

Efficiency of lamps are often measured in lumens per watt of electricity (l/w). Typically Incandescent lights produce 10-18 l/w while compact fluorescent lights can achieve 35-60l/w. Current LED fixtures typically achieve 30-40 l/w but the efficiency of LED fittings is expected to eventually produce fittings which achieve efficiencies of up to 160 l/w.

Both LED and CFL lights have longer lamp life than incandescent fittings. Projected lifespans for LED lamps being 35,000 – 40,000 hours compared to 8,000 – 10,000 hours for CFL lamps and 750-1000 hours for incandescent fittings.

EECA provides guidance on low energy lighting design.

Low energy lighting design can be optimised by the use of artificial lighting and daylighting modeling. For more information on commonly used modeling tools click here.

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