Technology for Energy and Water Efficient Houses


  1. Introduction

    See Also

  2. Eco-House
  3. Smart Apartment
  4. Author


13 Roma Mitchell Crescent

Eco-Living House

Three energy and water efficient homes are on display in Canberra from February 2006 to May 2007 in the "Eco-living Exhibition". The houses are at North Watson, in Canberra's inner north, near the main road to Sydney. The general public can visit during opening hours and school groups can book a tour. As well as be showcases for the particular products and designers, the display homes are GreenSmart certified, and intended to educate the public about an integrated approach to sustainable design for energy and water conservation. Designers of the houses, gardens and water systems will be on hand to answer questions at set times.

In April I looked at one of the houses, at 13 Roma Mitchell Crescent, and talked to the designer. In October I went back and talked to one of the suppliers of the energy and water saving equipment and at some of the other houses. While number 13 has, to my eyes, a severe industrial look, with the insulated concrete walls finished in a clear finish with joints showing, the other houses have been painted more like a "normal" suburban house. This is a matter of taste and an option for the owner. The exposed concrete is an aesthetic, as well as a way to show the energy efficient features of the building, which some may like. But this can all be hidden, if you prefer.

Evacuated Tube Solar Hot Water System

David Payne

David Payne

David Payne from Enviro Friendly Products Pty Ltd, explained the Evacuated Tube Solar Hot Water System.

Evacuated tube collectors are made of a series of modular tubes, mounted in parallel, whose number can be added to or reduced as hot water delivery needs change. This type of collector consists of rows of parallel transparent glass tubes, each of which contains an absorber tube (in place of the absorber plate to which metal tubes are attached in a flat-plate collector). The tubes are covered with a special light-modulating coating. In an evacuated tube collector, sunlight passing through an outer glass tube heats the absorber tube contained within it.

From "Solar heating thermal collectors, Wikipedia, 2006

This looks particularly good on a corrugated steel roof, as it consists of a row of silvery glass tubes. Each tube is double walled, with a vacuum between for insulation and a dark colored collector inside. The sun's heat is conducted to the top of each tube and used to warm water pumped up from a ground level tank. The result is a very efficient solar heater without the a large tank on the roof.

Heat Pump Hot Water System

Heat Pump Hot Water System

Heat Pump

One of the other houses in the display had a heat pump hot water system. This doesn't need to be mounted on the roof. It looks like a hot water tank with an air conditioner on the top, which is what it essentially is. The "heat pump" draws heat from the air, much the same way an air conditioner does and uses that heat to warm water. This is not quite as efficient as unit with a solar collector, but still much better than an electric water heater and much more convenient to install. The unit at the house is a Rheem, but there are also units from Quantum.

Hydronic heating system

Hydronic heating system

Hydronic heating

One house was heated by a hydronic heating system, which is a fancy word for hot water in pipes. In this case the pipes are plastic and embedded in the concrete slab. Flat panel radiators can also be used. The heat can be supplied by solar panels, a heat pump, or gas.

Water Tanks

Water Tank

Water Tank

The houses had one of just about every sort of water tank. Some were located under the eves to make plumbing simpler and colored to match the house. One was in the corner of the back fence out of the way, with the down pipe taken under the ground.

Compost Bins

Compost Bin

Compost Bin

Even the humble compost bin has a high technology make over at the eco-living exhibition. The wooden slats of the bins have gaps to allow air in, but in addition a slotted plastic pipe is added vertically in the middle. This allows the pile to be watered all the way through to keep the microbial action working to aid the composting.

Environmentally Sustainable Cluster Housing

The Eco-living display is impressive, but limited to detached houses on suburban blocks. What is needed is an example of environmentally sustainable cluster housing. We need examples of town houses and apartments incorporating these energy and water efficient features. The general public, builders and developers in Australia, could then learn about sustainable design principles for apartments. An example of this is my proposal for Environmentally Sustainable Cluster Housing, for Canberra's centenary in 2013.

The solar collectors and water tanks in the North Watson houses suit a large family home. But most Australian homes now have only one, two or three people in them. It is very expensive to install a heat pump in a one bedroom apartment and difficult to find the room for it. An alternative is to share one heater between several apartments, but then some way to share the cost is needed.

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