Elements of a sustainable home

Click on a pointer to the image to get more information on the sustainable design elements of a house

Reduce concreted areas Waste minimisation during construction Grouping and zoning of living areas Ventilation Orientation Build smaller and reduce site impact Air-tightness Thermal mass Universal access Image Map

Introduction

The performance of a house is built into its fabric and hence design is an important part of your journey towards building or renovating more sustainably. The design phase of a project is not just supplying the necessary documents to get the appropriate permits and meeting legislated building requirements, it also includes keeping an eye on the aesthetics, the impact of the house on the environment and enhancing the optimum liveability of your home.

A building designer or architect could help you to create the most appropriate design solution, using their expertise to balance your wish list with legislative requirements, sustainability, liveability and innovation.

Whether you are buying or building a new home, renovating or retrofitting, there are a number of websites, in addition to the resources in this guide, which provide good information.

Building new

Buying a new home

Renovating or retrofitting

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Build smaller and reduce site impact

Building a house with a smaller footprint reduces its building and operating costs, as well as its environmental impact. It also increases the amount of open space available for gardens which support wildlife, have a productive garden and enjoy nature.

The Ku-ring-gai area falls in Zone 5, warm temperate. Incorporate key responses for this zone to minimise the heating and cooling requirements of your home (see Your Home – Design for climate for key responses).

When building, consider the topography and existing vegetation cover. You can minimise disruption to landform and natural drainage contours by:

  1. retaining the natural slope of the land, thus minimising excavation
  2. lightweight construction using elevated platforms on sloping sites instead of cut-and-fill concrete slabs on earth
  3. retaining significant trees and other features such as rock outcrops.

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Orientation

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Traditionally, the orientation of houses has been dictated by the orientation of the block of land and its location of the street. The best orientation is achieved by positioning the house to capture the benefits of passive solar design, in the areas where you spend most of the time, i.e. the living areas. Orientate the house to make the best use of the sun’s path and prevailing wind patterns.

The best approach is to maximise glazing to the north for winter solar gain (with shading in summer) and minimise glazing to the east and west for lower summer heat entry.

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Grouping and zoning of living areas

North-facing rooms are ideal for living areas, such as family rooms, lounge rooms and kitchens. By grouping like rooms together, it is easier to control the heating and cooling of different areas within your house. You can set varying temperatures in different areas of the house, for energy savings as well as the comfort of residents with differing needs.

Grouping ‘wet areas’ such as the bathroom, toilet and laundry together, can reduce plumbing costs and hot water heat-loss.

Besides making sense thermally, zoning different areas of the house is also helpful acoustically, allowing different family activities to occur at the same time. Doors, walls or other features allow groups of rooms to be closed off and allow to creation of smaller spaces for heating and cooling.

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Thermal mass

The introduction of air conditioning has changed the way we manage the internal comfort of our homes. The concept of using building mass and form, called thermal mass, to provide comfort is often ignored in favour using energy to regulate temperature. With rising energy prices and the impact of energy-related greenhouse gas emissions, this approach is not cost effective.

Thermal mass is the amount of material present in the house that absorbs and retains heat. Walls of concrete, brick, earth and stone have high thermal mass whereas fibro and stud walls have little. Similarly, floors made of dense material such as concrete tiles and stone stores the heat from sunlight which falls on it.

Thermal mass is useful in absorbing winter sun on the north side of a house and radiating the heat back into the room during the late afternoon and night, thus reducing the need to use heaters or fires in winter. In summer, you can use awnings or blinds to shade this wall or floor that serves as thermal mass and keep it cool. A combination of brick walling and timber framed walling can be used to increase internal thermal mass where it is needed and keep the house from heating or cooling too much.

Some simple, easy ways to retrofit thermal mass are:

  • Place bricks, concrete blocks, sealed containers with water or damp sand along an external sun-facing wall that overheats
  • Move a bookshelf full of books against the wall in the room
  • Grow plants on a trellis near or against the overheating wall.

One thing to be aware of is the ‘thermal bridge effect’. If a concrete slab continues from the room to the balcony, the outer portion exposed to the sun in summer, acts as a bridge to the inner part, heating the room unintentionally. Make sure you add a thermal break or insulate the edge of the thermal mass to avoid this.

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Air-tightness

Air-tightness does not mean that the house is hermetically sealed but that infiltration is controlled. Draughts happen where there are unwanted gaps in the construction of your home or where openings are left uncovered. Around one-third of home heating can escape through gaps and cracks, so draught-proofing is an easy way to reduce the need to heat and therefore your energy bills. If warm air can’t get out, neither can it get in, which means your cooling costs in summer will also be lower.

Energy efficiency assessors can help you detect insulation inefficiencies, dampness and air leakages using tools such as thermal imaging and blower door tests. You can also use an infrared thermometer to find heat/cold infiltration points. An infrared thermometer is part of the Save Power Kit you can borrow from your local Ku-ring-gai libraries. Great results can be gained by the simple task of sealing up the joints in the construction. Areas to look for draughts from gaps include:

  • windows
  • doors – including keyholes and letterboxes
  • loft hatches
  • electrical fittings on walls and ceilings, e.g. recessed lights, switches and wall-mounted air-conditioners
  • gaps between floorboards
  • pipework leading outside
  • joints of the floors and walls
  • chimneys
  • wall vents (a legacy from when we had unflued gas lights) and exhausts.

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Air-tightness can be improved by:

  • sealing gaps around doors and windows
  • repairing damage to window frames and ensuring closing mechanisms work properly
  • ensuring the loft hatch fits into its aperture and applying draught stripping between hatch and frame
  • using a removable chimney balloon or open/close chimney damper plates where present
  • sealing gaps around cables and service pipes that pass through external walls, floor or ceiling, and
  • laying rugs on bare floors.

An airlock entryway (vestibule) is another way to reduce the amount of air infiltration and heat loss when an exterior door is opened. This feature can be used to improve comfort and energy-efficiency of homes in cold weather and also reduce air-conditioning use and costs in hot weather.

An airlock entryway has two airtight doors that reduce the amount of air infiltration and heat loss when the exterior door is opened. The buffer area created between the doors blocks the wind and improves energy efficiency.

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Ventilation

‘Build tight, ventilate right’ should be the motto to adopt when designing your home. When planning door and window locations for your house, consider the directions breezes come from and place openings in these areas.

Locating windows opposite each other will allow air to flow more readily through your house, known as cross-ventilation. Where cross-ventilation is not possible, mechanical ventilation systems can be retrofitted. Systems such as Xchangeair, Ventis, Odyssey and Smartheat manage radiant heat recovery, heat extraction and air transfer.

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Roof design also aids in controlling heat flow into dwelling, reducing the need for artificial cooling. You could have roof-ridge vents, eave (slot) vents and vents fitted to soffits and gable ends of the roof to allow a cross flow of air through the roof cavity.

Heat recovery ventilators (HRVs) are controlled ventilation systems that use the heat from the outgoing stale air to heat or cool incoming fresh air. They can be quite expensive but are worth considering if you are renovating.

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Reduce concreted areas surrounding the home

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Built surfaces are usually made of non-reflective and water-resistant materials such as concrete which tend to absorb and release heat. This heat island effect can be minimised by reducing concreted areas and using permeable or open-grid pavement.

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Waste minimisation during construction

Use pre-fabricated, modular and pre-cut components

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Doing this saves construction time and no waste is generated on site. Resource use is more efficient at the factory compared with a building site, where off-cuts are often dumped or burnt.

 

Use of modular and pre-fabricated components reduces wastage. For instance, wall framing and roof trusses can be pre-cut, pre-nailed, and delivered as a correctly sized unit ready to be installed, reducing timber waste significantly.

Designing room-sizes to co-ordinate with the standard sizes of floor, roof and external cladding materials will reduce the need and cost of customising materials. So for materials sized in 600mm, if you design to a module of 300 or 600mm, fewer panels need to be cut and there is less waste and lower costs.

Build for deconstruction

This ensures that when future modifications or decommissioning occurs, the entire structure can be taken apart and its components reused with ease and minimal waste.

Avoid packaging

Specify your exact requirements to manufacturers and suppliers. This can assist in avoiding over-packaging goods or unnecessary packaging, as well as needless surfeit of materials.

Material storage during construction

Set up appropriate storage arrangements to guard against product degradation or damage from weathering or moisture. You can avoid storage by requesting suppliers to deliver materials as and when needed.

http://www.remodeling.hw.net/organization/deconstruction-reuse-network

Separate materials for the tip and recycling

In the case of knockdown/rebuilds, make an arrangement with recycling contractors to provide clearly marked bins for material separation. Make sure that building contractors are aware of the placement of the bins and their responsibility to separate materials. If there is insufficient space to separate materials on site, check if you can send mixed loads to a sorter for recycling.

Make sure that waste contractors safely dispose unavoidable waste in licensed landfills. Keep  documentation such as landfill receipts.

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Universal access and liveability

Initial design process with liveable design guidelines can benefit home occupants through various stages of life. Such design elements, which range from garage size (for wheelchair accessibility) to toilet locations and bathroom wall strength (for grab-rails to be installed at a later date), allow for cost effective adaptation to suit young families, elderly, disabled or injured occupants.

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