Green building and sustainable architecture

The terms “environmental design”, “green home design” and “sustainable architecture” are just a few of the terms that people use when trying to describe a home that is designed to minimise it’s impact on the natural environment. In this article we use the term “environmental design”.

Good environmental design positively effects the thermal comfort of a building allowing the occupants to be comfortably warm in winter and cool in summer – with minimal energy usage.

There are 6 main areas that need to be considered when planning your eco friendly house or renovation. The information given in this article applies to sites at a latitude of approximately 32°, which covers the greater Sydney area in NSW, including Newcastle and Wollongong, and Perth, in Western Australia.

 

Design

Ideally you should purchase a site that is flat and has its backyard facing north towards your view. This will make designing an environmentally friendly house or passive solar home much easier.

 

Sun and orientation

You will need to spend a good amount of time assessing direct sun penetration onto your site before you start designing your passive solar home.  If it were practical, and you oriented all the internal spaces in your home to north, it would be relatively straightforward to build a green home that was thermally comfortable all year round. However in the non-ideal “real-world” this is rarely possible. A great book to use when planning around sun and shade for you building is “Sunshine and Shade”, written by R. O. Philips of the CSIRO. Use the basic rules listed in this book to aid you when planning the various spaces in your home.

 

Sun control devices

There are many methods of controlling sun penetration in your home helping a house stay cool in summer and warm in winter.

Roof overhangs: For homes that are drenched in full sun ensure that all windows have a standard window and door shading depth of 900mm.  600mm is the normal project home depth and that is not enough.  This depth can be slightly altered depending on the orientation of the external walls to north.

Other control devices: If you have no choice in how you orient your living areas, and are forced, for example, to orient them towards the west (the harshest of all options) you will need to get creative. One solution is to plant deciduous trees to the west about ten metres from your house.  This will block hot afternoon summer sun and allow winter afternoon sun to penetrate through to your home. If this is not an option due to views or council regulations, the best solution is an operable (adjustable) window device like an awning or louvre system.

 

Room orientation

If you have shading on your site you need to think about the room type and design to get the optimum sun penetration into the space; e.g., locate laundries, bathrooms and storerooms to the west or south.  These rooms can be physically cut off to control the hot western sun or the cold resulting from a southern facing orientation. Bedrooms work best located on the east because most people love being or drenched in morning sunlight. (However a southern orientation is a worth considering for shift workers, because the bedroom will then be darker.)  Leave the north to living areas as people spend most of the daytime in these areas.

 

Insulation

To save on heating and cooling costs in your new green home it is essential that all your external walls and ceilings are insulated.  All cladding types have an R-value, the higher the R-value the longer it will take for the outside temperature to enter you home.

Many houses today are timber framed and without any extra insulation these homes will not be hot and cold in the wrong seasons but it will also rate poorly with BASIX (BASIX is the Building Sustainability Index.).  There are too many products to name, but insulation generally come in the form of “batts”, air cell blankets (like bubble wrap), loose pulp, and “sheets”.  Heat is lost primarily through the ceiling of a home, then the walls and windows, and lastly the floors.  If your site faces a windy direction, and is located at the top of a hill, your floors will need to be insulated.

Sarking is a reflective fabric that reflects heat away from the roof and external walls and it should be laid with the reflective side facing outwards.  Roof sarking often forms part of an insulative blanket that is laid on top of the roof trusses and under the roof battens.

There are many new products on the market that are a “sandwich” format product (cladding on one side, a finished lining on the other, and insulation in the centre).