Adapting to climate change
A home provides its occupants with a refuge from the climate, but as the climate changes, the home may not be able to meet this need. In general, temperatures are increasing, sea levels are rising and extremes in the weather are more likely. If climate change is considered when a home is being designed or altered, it is likely to remain comfortable for longer, possibly for its whole life.
Although it is important to minimise the extent of climate change through mitigation measures such as reducing greenhouse gas emissions, the opportunity to avoid the impacts of climate change altogether has passed (DCCEE 2010). If we want to ensure that our homes remain ‘as safe as houses’ we need to consider and adapt to the future climate.
In Australia the average life of a brick home is 88 years and a timber home is 58 years (Snow and Prasad 2011); many last much longer than this. Decisions that are made about homes today will therefore continue to have consequences for many decades.
Photo: Karen Disney
Many old homes are loved and used still.
Australia, because of its size, has a range of climates which will vary in their response to climate change. In general there will be:
- higher temperatures
- higher annual rainfall in the north, lower rainfall in the south
- longer periods of drought
- increased number of days of very high, extreme or catastrophic fire danger
- increased risk and intensity of severe weather such as tropical cyclones, floods, hailstorms and droughts.
Adequate insurance will help to protect you financially against extreme events. To ensure that it meets needs, you should:
- know the specific impacts relevant to your region
- review your current insurance
- consider seeking professional advice.
You already consider the future when acquiring, building or just living in a home: for example, how livable will it be, will it accommodate a growing family, is it affordable, and is it likely to increase in value. You should also ask what the climate will be like and whether the home will suit these conditions. Take into account your objectives, how long the home is intended to last and any regulatory requirements.
Noting that the impacts of climate change will vary from region to region the best estimates are that by 2030 Australia will face:
- about 1°C of warming, resulting in more heatwaves (CSIRO and BOM 2007; Australian Academy of Science 2010)
- up to 20% more months of drought (CSIRO and BOM 2007)
- up to 25% increase in days of very high or extreme fire danger (CSIRO and BOM 2007)
- increases in storm surges and severe weather events (CSIRO and BOM 2007; Australian Academy of Science 2010)
- a sea level rise of about 15cm (Australian Academy of Science 2010).
If emissions continue unabated the impacts are likely to be more severe in the future (Australia Academy of Science 2010).
Research the likely climate change impacts for your location and base your decisions upon your findings. There are many sources of information about climate change, including your local council, who may also be able to provide information about planning controls that could guide home design.
One central source is www.climatechangeinaustralia.gov.au. For further information about impacts at a state or territory level, see relevant government websites.
|Note: The detailed information about the effects of, and level of preparation required for, climate change will differ between jurisdictions.|
|Australian Capital Territory||www.environment.act.gov.au|
|New South Wales||www.environment.nsw.gov.au|
Planning for climate change impacts
Good design for a changing climate is design that is flexible enough to adapt to prevailing conditions while optimising the occupants’ comfort and the house’s livability (see Design for climate).
When considering design or redesign of a home, ask the following questions:
- What are the climate variables that could affect the building?
- Will climate change impacts affect the site and the building?
- What are the likely consequences to the home in the event of extreme weather?
Strategies set in place early will reduce future costs; linking actions into build, renovation or repair cycles will also minimise costs (Major and O’Grady 2010; Snow and Prasad 2011). Decisions can be made without accurate predictions of future climate change. A range of plausible scenarios combining climate projections will help to explore potential outcomes and risks (Snow and Prasad 2011).
Seek professional advice (e.g. from your architect or designer) before acting. Once the options have been identified, compare them against other factors:
- How effective will the option be over the life of the house? Is it flexible enough to respond to climate conditions?
- How practical is the option, and is it easy and relatively inexpensive to maintain?
- Is it compatible with the existing dwelling?
- Are there other benefits, or undesired side effects, that arise from the option?
Building flexibility into the process means that changing climate conditions can be taken into account (Major and O’Grady 2010). The design incorporates pathways for adaptation in the future, which can be taken as needed without too much additional expense. Examples of such ‘flexible adaptation pathways’ include:
- ensuring that there is enough space in your land to include extra water storage for changing water availability
- building more substantial footings under a deck so that it can easily take the weight of a roof if in future more shade is needed around the house as temperatures rise.
It may not be necessary to build a fortress-like home — one that is capable of withstanding all impacts while complying with building regulations. It might be an option to build a home that is:
- of limited life to minimise financial outlay, i.e. a home which the owner is willing to lose, either in part or whole, for example in areas where extreme storms are likely to occur
- transportable, or modular, and able to be moved and used elsewhere if the site becomes unsuitable, for example due to sea level rise.
The best adaptation actions are win-win or low/no regret, i.e. they may offer other benefits. For example, concrete floors which have high thermal mass have the potential to keep the home warm or cool, and also recover well should the house be flooded (Snow and Prasad 2011).
Adaptation and mitigation can complement each other and together reduce the risks. Conversely, ensure these actions do not undermine each other. For example, adaptation actions for one climate change impact could cause a home to be less well adapted for other impacts (‘maladaptation’) or could also create a home that is less livable for changing lifestyle needs (see Design for climate). These effects should be avoided or perhaps negated through design or materials choices, as shown in the table.
|Action||Potential unintended result||Example of solution|
|Ensuring roofs are designed to cope with high intensity rainfall events||May increase roof complexity, which increases the chance that embers will lodge during bushfires||Ensure roof design is simple and minimises the likelihood that embers will be caught in the roof|
|Installing and using a large air conditioner to cope with hotter temperatures||Will produce more greenhouse gases because of increased power needs||Incorporate passive design or use alternative power sources|
|Insulating homes and sealing against airflow to minimise loss of heat for energy efficiency||Could change the capacity of the dwelling to lose heat in summer||Design house to allow increased airflow during the relevant periods|
|Raising floor levels to avoid flooding||May disturb acid sulphate soils by changing the level of the watertable if solid fill is used||Do not use solid fill in areas that may have acid sulphate soils|
|Could reduce accessibility for the less physically able||Consider including ramps or other options|
Adaptive strategies for building design
Adaptive strategies should be considered for these climate change variables:
- temperature increase and heatwaves
- cyclones and extreme wind
- severe thunderstorms and high intensity rainfall events
- sea level rise and storm surge
- low rainfall.
Many of the options outlined below are from Snow and Prasad (2011). Seek advice from a professional, e.g. an architect or designer, before making changes to the design or redesign of your home.
Temperature increase and heatwaves
One of the main expected effects of climate change is increasing temperature and a greater number of extremely hot days (CSIRO and BOM 2007; Australian Academy of Science 2010).
|Source: CSIRO 2008|
The need for keeping your home cool during the summer months will be greater, particularly during extreme heat. Power failures, and the consequent discomfort, may be more likely during extreme heat events.
On the other hand there should be less need to heat the home in winter: good passive design will help to capture these savings (Camilleri 2000). It can lessen the need to rely on air conditioners and heating and can cool the home without increasing power use or producing greenhouse gases.
There are many options for improving the passive thermal properties of homes:
- Use the most energy efficient stoves, fridges, lighting and other equipment to lessen internal heat gains from sources.
- Use reflective glazing, external shading and reflective roofing.
- Capture natural ventilation.
- Install whirlybirds to remove heated air from the roof cavity.
- Use green roof design.
- Increase insulation and add thermal mass.
- Use photovoltaic, solar, biomass and wind-powered cooling technology.
- Build your home with an appropriate orientation to the sun.
(see the section Passive design; also Green roofs and walls; Heating and cooling)
A significant increase of very high, extreme or catastrophic fire danger days is expected. Minimising fuel loads — things that burn — close to the home will reduce the risk (Gibbons et al. 2012). Keep yard growth trimmed, clear dead wood and rubbish often and use metal rather than wood for fences.
There are several architectural ways to minimise the risk of the home burning and/or maximise the safety of the occupant:
- Install shutters and sprinkler systems in high risk zones.
- Ensure that the roof minimises the risk that burning embers will be caught.
- Use building materials that are fire resistant.
Shutters can cover large areas.
Cyclones and extreme wind
Although the total number of cyclones is expected to decrease, high wind events and tropical cyclones of greater intensity may increase; their range could also move further south (CSIRO and BOM 2007).
Extremely strong winds can place a great strain on buildings; any damage to homes can cause subsequent damage to their contents. To minimise the risks:
- use improved fixing systems in the roof structure and the subfloor (increasing the strength in one area may cause another area to fail: consult a professional)
- design buildings to minimise the wind loads
- use impact resistant materials for external cladding
- ensure building materials are largely waterproof and drainage design is effective, particularly for flashing, vents and penetrations.
In an established home, ensure the structural fixing elements have not been compromised by corrosion or previous cyclones (Snow and Prasad 2011).
Severe thunderstorms and high intensity rainfall events
An increase in high intensity rainfall events has been projected but it is difficult to predict whether thunderstorms — hail, wind and tornados — will increase in number and/or intensity. Indications are that hailstorms will increase over the south-east coast of Australia, potentially leading to impact damage and moisture penetration.
Given the significant damage that hailstones can inflict it may be worthwhile preparing homes for the impacts. Options for reducing damage include:
- selecting roof materials that are impact resistant (e.g. metal rather than terracotta)
- designing or installing appropriate window protection.
Consider ‘the four Ds’ when managing water flow about the home to reduce damage from high intensity rainfall: deflection (keep it out), drainage (get it out if it gets in), drying (allow wet materials to dry) and durability (select materials that can withstand the effects) (Walford 2001). Options include:
- designing or installing window protection
- ensuring roofs are well maintained
- creating greater capacity to detain and harvest water from a deluge
- selecting materials that can withstand moisture
- ensuring there are drainage cavities in walls
- improving the detailing to roof edges, open decks, walls and joinery, retaining walls, floors, balconies, wall−roof junctions and roofs.
- ensuring internal and box guttering can withstand a 1-in-100 year rainfall event.
Capturing the extra rain and using it to irrigate green spaces may also offer advantages, such as reducing heat island effects (built-up areas become hotter than nearby rural areas).
The projected increase in rainfall intensity is likely to result in more flooding events. Flooding can be localised or associated with a river system. Possible impacts include water damage to the home and its contents, the undermining of foundations and the contamination of the home by sewage or mud (Snow and Prasad 2011).
The risk of flooding to homes can be reduced by not building in areas which could flood, i.e. along river floodplains and on low-lying coastal areas. Other options to reduce flooding risk include:
- exceeding minimum floor levels
- constructing multistorey homes and using the lower level for non-living areas
- using water resistant materials (e.g. concrete, fibre cement)
- ensuring that drainage allows water to escape after the flood
- raising vulnerable equipment (e.g. service meters)
- building a limited life dwelling to minimise financial outlay
- building a levee around the house
- designing a garden that will safely redirect water.
Raising floor level heights may not only reduce the risk of flooding but could also have beneficial effects on passive thermal design (e.g. by increasing subfloor circulation to cool the house). However, using fill to increase the height of the floor may disturb acid sulphate soils so make sure you have a sound knowledge of the site (see Choosing a site).
Source: © Cox Rayner Architects
Design of a home that could cope with flood conditions.
Sea level rise and storm surge
Although the coastline of Australia has changed throughout time it has been fairly stable for the last 6,000−7,000 years (DCCEE 2009). More recently, between 1950 and 2000, global sea levels have been rising by an average of 1.8mm per year, a rate that has increased to over 3mm since the mid-1990s (this rate varies significantly around Australia) (CSIRO and BOM 2007). With 85% of the Australian population living in coastal regions, susceptibility to both sea level rise and storm surge is concerning (Snow and Prasad 2011).
Storm surges occur when intense onshore winds push waves harder against the coast, and have the most impact during high tides. Other factors that increase the impact of storms are wind strength and direction and coastal characteristics (CSIRO and BOM 2007).
As a result homes near coastlines and estuaries may thus be more likely to flood and may have to cope with rising watertables. Greater foreshore erosion could also expose more homes to the impacts of storm surges and sea level rise (particularly for sandy coasts). Stormwater systems may be less able drain into the sea and therefore may cause flooding further inland (Camilleri 2000).
Source: CSIRO and BOM 2007
Characteristics of tide, waves and storm surge combined.
Three strategies can deal with sea level rise and storm surge: protect (e.g. construct sea walls), accommodate (live with the impact) and retreat (DCCEE 2009; Snow and Prasad 2011).
Options for accommodating the risk or retreating include:
- elevating the home
- ensuring the parts of the home that may flood can cope (e.g. the foundations)
- building a limited life home to minimise financial outlay
- building a transportable home.
For further information about the vulnerability of the coastline of Australia see Climate change risks to Australia’s coast: a first pass national assessment (DCCEE 2009) or consult local government risk assessments.
In areas where rainfall will decline, droughts will be more severe. Flows into water supply catchments will decrease and evaporation of water and transpiration from trees increase due to higher temperatures (CSIRO and BOM 2007).
Minimising water use and maximising water efficiency and capture are essential for ensuring there is enough water to maintain lifestyles (see the section Water).
|References and additional reading|
|Australian Academy of Science. 2010. The science of climate change: questions and answers. www.science.org.au|
|Camilleri, M. 2000. Implications of climate change for the construction sector: houses. BRANZ study report no. 94(2000). New Zealand.|
|Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Bureau of Meteorology (BOM). 2007. Climate change in Australia: technical report. www.climatechangeinaustralia.gov.au|
|Commonwealth Scientific and Industrial Research Organisation. 2008. Projections of days over 35°C to 2100 for all capital cities under a no-mitigation case. Data prepared for the Garnaut Climate Change Review, CSIRO, Aspendale, Victoria. www.garnautreview.org.au|
|Department of Climate Change and Energy Efficiency (DCCEE). 2009. Climate change risks to Australia’s coast: a first pass national assessment 2009.|
|DCCEE. 2010. Adapting to climate change in Australia: an Australian Government position paper.|
|Garnaut, R. 2008. Garnaut climate change review. Cambridge University Press, [additional reading now found on www.garnautreview.org.au].|
|Gibbons, P, van Bommel, L, Gill, A, Cary, G, Driscoll, D et al. 2012. Land management practices associated with house loss in wildfires. PLOS ONE 7(1).|
|Intergovernmental Panel on Climate Change (IPCC). 2001. Climate change 2001: synthesis report. A contribution of working groups I, II, III to the third assessment report of the intergovernmental panel on climate change, R. Watson and the core writing team (eds). Cambridge University Press, Cambridge.|
|Major, D and O’Grady, M. 2010. Adaptation assessment guidebook, app. B, vol. 1196, Climate change adaptation in New York City: building a risk management response. New York City Panel on Climate Change. Annals of the New York Academy of Sciences. www.nyas.org|
|Morenga, L, Maplesden, F, Collins, M and Gaunt, D. 2001. How do builders rate wood in intensive residential developments? NZ Timber Design Journal, 10(3). www.timberdesign.org.nz|
|Snow, M and Prasad, D. 2011. Climate change adaptation for building designers: an introduction. Environment design guide, EDG 66 MSa. www.environmentdesignguide.com.au|
|Walford, G. 2001. Rain screen technology. New Zealand Timber Design Journal, 10(3). www.timberdesign.org.nz|
Department of Climate Change and Energy Efficiency, 2013