Solar benefits

Lesson #2:
What are the benefits of solar passive design?

Everybody needs a shelter. Protection from the elements, an escape from the rest of the world, a place to call home. At Paton Constructions we believe in building sanctuaries that make the most of nature’s benefits by reducing reliance on artificial heating and cooling, and taking advantage of views.

It’s estimated that around 38 per cent of energy consumed by Australian homes is for heating and cooling. Using solar passive design can dramatically reduce this figure.

Solar passive design is a key element in the homes we build. Not only does it minimise energy usage and significantly reduce energy costs, a solar passive home designed by Paton Constructions is a light-filled space offering an uplifting, comfortable living environment.

The most critical features of solar passive design are:

• Orientation of the building
• Thermal mass
• Insulation
• Draught sealing / ventilation

Orientation

It’s important to tailor design to climate, and in the Canberra region this means positioning a home to be north-facing (true north, or up to 8º east of true north).

This allows the lower winter sun to penetrate the building as deeply as possible, providing much-needed warmth and light during the colder months. During summer our houses are shielded from the higher-angled sun by the use of eaves. Locating bathrooms and laundries on the western side of a home will also help protect living areas from summer sun. Clever planting of deciduous trees can further complement solar passive design by offering shade protection of walls and windows in summer, and by allowing winter sun to warm the house in winter.

Thermal mass

Thermal mass refers to a material’s ability to retain heat energy.

In winter a higher level of thermal mass can store more energy, which means more heat.

In summer a higher level of thermal mass, once cooled by cool night air, will need more energy to heat that mass during the day before the living space begins to heat up.

Paton Constructions homes are designed using a concrete slab as the building’s base, and with brick for some internal walls. Both of these elements act as thermal mass. In winter energy from low-angled sunshine is absorbed by the slab and walls, and then gradually released to keep the house warm overnight. In summer the slab and internal brick walls are protected from direct sun by eaves which also shade windows and external walls. Cooler temperatures from the ground below the slab will also help keep the house cool, creating a comfortable environment inside the building. The ground under the concrete floor slab acts as a connected extension of the slab.

Insulation

In winter the aim of insulation is to reduce heat loss – heat from the sun which has been stored in the home’s thermal mass.

In summer the aim is to reduce heat gain, and insulation is important in allowing the home to retain night-time cool air (or cooled thermal mass) as well as preventing heat from entering the home.

Paton Constructions homes incorporate a number of systems to achieve optimal insulation. Up to 25 per cent of winter heat is lost through walls, and to combat this our homes are built with a very high level of external wall insulation. Wall cavities are filled with R2 grade (and better) insulation. We use R4 grade batts and/or reflective sheeting in roofspaces, minimising heat loss which in a non-solar passive designed home can be up to 35 per cent. Our designs can also include double-glazed windows and doors which are particularly appropriate to Canberra’s cold winters and leafy environment – they prevent up to 35% heat loss without the need for additional window coverings which block out the view.

The concrete floor slab perimeter is also insulated as thoroughly as possible, and as vertically deep into the ground as possible.

Draught sealing / ventilation

Paton Constructions homes are designed to give you control over ventilation throughout the seasons. When the weather is cold, any gaps in construction will allow cold draughts to enter the house – in most homes up to 25 per cent of winter heat loss is through air leakage. We use a variety of methods to ensure our homes are able to be sealed in winter, including installing well-made doors and windows with airtight seals and draught-proofing strips. We try and achieve an airtight space to live in.

Conversely, in summer ventilation is crucial to providing a comfortable living environment. Our designs incorporate cross-ventilation and screened windows and doors to allow airflow.

Other systems to support solar passive design

There are many appliances and systems available to complement solar passive design and further reduce energy consumption and costs, including

Photovoltaic (solar) panels to produce electricity, modern and efficient solar hot water heaters, and water saving taps and shower spouts.

In recent years these appliances and systems have become a more common feature in homes and this, together with government-supported rebates, has had a favourable impact on price.

So what should you try to achieve for your living space ‑ your shelter?

1. An airtight shell
2. Insulation – high levels for wall, ceiling and roof
3. Sun – maximum sun penetration in winter, minimum sun penetration in summer
4. Thermal mass – maximum thermal mass inside your living space
5. A light-filled space for well being
6. Views to the outside world where this is possible

Incorporating these design elements will give you a comfortable and inviting shelter.

Paton Constructions would love to design and build your solar passive sanctuary. We can also provide solar passive design solutions by renovating an existing home. Contact Leslie Paton to discuss – 02 6298 1900 / leslie@patonconstructions.com.au