Sustainable dwelling design – Top 10 tips
- Windows performance – Single glazed aluminium windows generally achieve R0.17 and the best available thermally broken aluminium windows can be three times better at R0.5. Be selective with window sizes and location. Windows performance is discussed in U values which are the reciprocal value of the R value i.e. 1/0.17 gives a U value of 5.8 and 1/0.5 gives a U value of 2. A lower U value is preferable.
- Walls and Windows – walls generally have R2.0-3.0 insulation value to ensure a reasonable energy rating. Bearing in mind the window R values described in 1 above, windows are in the order of 1/10th – 1/6th as good at insulating as walls. Avoid numerous excessively large windows. Also ensure insulation is installed correctly. Heat travels through gaps like noise does – so a small gap can let a lot of heat in or out.
- Window locations – Ideally locate larger windows on the north elevation rather than south elevation. Also reduce the size of east and west glazing or provide external adjustable vertical shading.
- External shading is significantly more effective than internal blinds. External adjustable vertical shading can be effective where balconies provide access to blinds. Blinds incorporated in the leading edge of the eave or balcony above are a very easy to access and use shading solution. This vertical shading is the most effective for east and west facing windows. Horizontal shading can be effective for north facing windows as, if designed with an appropriate projection distance, it should keep out summer sun while admitting lower level winter sun.
- Window tinting – window tinting is common in commercial building where shading is not incorporated. Window tinting should be avoided always on south elevations, and generally avoided on other elevations with adjustable shading preferred, as tinting keeps out desirable winter passive heat gains as well as less desirable summer heat.
- Insulating under suspended slabs – a concrete slab typically provides approximately R0.15 insulation value – very little insulation. The total star energy rating of apartments sitting on a suspended concrete slab above a carpark, can be improved by R0.5 – R1.0 by adding R1.0 – R1.5 insulation to the underside of this slab. Remember to insulate under floors where there is a non conditioned (heated or cooled) space below. Insulation can be reflective polystyrene board, firmer bulk insulation blanket, rigid board or spray on solutions.
- Preliminary energy ratings or modelling – Preliminary energy ratings or computer modelling is the best way to get a feel for the performance of an individual dwelling or apartment. A final certification energy rating will eventually be required based on the final design of the dwelling.
- Openable windows and breeze paths – ensure all windows have a substantial openable component and ideally windows on multiple facades to allow good, direct breeze paths for natural cooling. A good breeze will create the feeling of a 2-5 degree temperature reduction. Ceiling fans have the same impact and are effective in bedrooms at all temperatures and living spaces for all but the hottest days. Running ceiling fans reduce the days when air-conditioning needs to be considered – generating significant energy use savings.
- Internal clothes drying rail – Include a European laundry as a separate cupboard off the hallway i.e. not within a bathroom – where a robe type hanging rail can be hung to remove the need for a power consuming electric clothes dryer. Hanging clothes on coat hangers or underwear peg wheels on this rail allows simple passive drying of clothes. Fit the rail 2150mm above floor level and it can be reached by most people, while still fitting a clothes dryer underneath if the occupants really want this.
- Energy efficient services – At town planning stage many councils will require either energy efficient solar boosted hot water services or heat pump hot water units, or PVC solar panels providing enough power to cover the some of the power demands in the building – e.g. of the common area corridors and entry.
These suggestions mainly cover energy efficiency suggestions, but there are many other aspects to consider in sustainable design:
- Water saving solutions – efficient fixtures, water tanks
- Water Sensitive Urban Design which considers the quality of water leaving a site and entering our drains, creeks and the Bay
- Selection of more environmentally friendly material choices,
- With better sealed buildings, ensuring off gassing from modern materials is minimised is now more important
- Waste minimisation during demolition, construction and facilities and planning to ensure similar during operation
- Designing to more simply facilitate alternative transport options to car use
- Maintaining and enhancing the urban ecology
- Community building design ideas and Innovation