Sustainability Assessments

Reduce your energy costs and help the environment and live more comfortably

If you would like to reduce your running costs and reliance on artificial heating and cooling, as well as conserve water, we can provide a detailed assessment of your house plans or existing residence to advise you on cost effective options to improve the thermal performance and water conservation of your home.

Case study: Sustainability Assessment and project management to an existing 1930's Art Deco renovation and extension.

Brief: To advise on incorporating sustainable design measures and product selection for an existing 1930’s residence that was in the design phase of being extended and renovated. 

History: The original 1930's residence which was located in Wembley was typical for its era, consisting of 2 bedrooms, 1 bathroom and a lean-to sleep-out. The rooms were poorly orientated, dark, cold in winter and hot in summer.

The original residence was rated for energy efficiency and achieved a energy rating of only 1 star. The more stars a home rates, the better the thermal performance will be which results in less reliance on mechanical heating and cooling thus saving money on running costs.


The main living area pictured right formed part of the rear extension which was orientated to face north. This was to allow the low angled 34-degree sun in the colder months of winter to penetrate the living area through the large north facing windows and heat up the thermal mass which consisted of a concrete slab on ground covered in dark travertine stone tiles and internal masonry walls. As the thermal mass heats during the day it is then re-radiated into the living area during the cool winter night.

To prevent the high angled 81-degree hot summer sun penetrating the north facing glass and overheating the residence, the correct eaves width was incorporated to provide summer shading as shown in the cross section drawing.

Smaller south facing windows with casement sashes were installed to the living area to capture cooling south westerly breezes in summer and ensure good cross flow ventilation.

High performance window frames and glazing units were specified which consisted of cedar timber frames with minimum 6mm laminated double glazed sealed units. A low E coating was incorporated to the double glazed units in the living area for its reflective properties of retaining heat within the home during winter. Timber frames were selected over aluminium frames for their superior thermal performance. The installation of heavy block-out drapes provided further resistance to heat flow transfer. 

The outdoor covered alfresco was situated on the east side of the living area to ensure that the living area was bathed in natural light and the warm northern winter sun was not restricted from heating the thermal mass.

Older homes generally have large amounts of uncontrolled air leakage through open chimneys, unsealed wall vents, windows and doors. Therefore, draft seals were installed together with balanced flue gas log fires which do not require wall and ceiling vents like general gas heating does.

Thermal resistance to heat flow through the ceiling was provided by R3.5 insulation batts, whilst Anticon blankets and reflective sarking were installed directly below the roof cladding.

Energy efficient appliances and variable speed pumps were selected. The use of pendant lighting and IC LED downlights greatly reduced air leakage commonly associated with the poor performance of halogen downlights or non-IC rated LED that penetrate the ceiling and require a 200mm clearance from insulating materials.

The installation of ceiling fans to all bedrooms and the family room provides low cost cooling to supplement the solar passive design principles.

A 3kW solar panel system was installed on the northern elevation to take advantage of Perth’s sunny climate and reduce energy costs. 

Water conservation was achieved by connecting all the roof stormwater run-off into a large underground water tank installed below the front lawn area that feeds the water supply to the laundry and WC's. 

Water efficient plumbing fixtures were selected through-out. The installation of a hidden pool blanket was provided to reduce evaporation.

A low maintenance and drought tolerant native verge and front landscaped garden was incorporated to further assist in water conservation with higher water use plants such as fruit trees, herbs and ornamentals grouped together at the rear of the property. 

The result: The completed residence has now achieved an energy rating of 8 stars despite its large (383m2) footprint. This has greatly reduced the occupier’s reliance on artificial heating and cooling and provide considerable cost savings into the future.