Chapter 3 Climate Applications and Services

Building Design

Climate information is essential in most aspects of building siting and design. Energy efficiency, structural integrity, even protection of verandahs and loading zones from wind-driven rain are among the climate-sensitive aspects of building design.

Low-energy building design

Many architecture schools place considerable emphasis on the use of climate data for design of climate-responsive buildings. Consulting practices such as the University of New South Wales’ Centre for a Sustainable Built Environment, Energy Partners and Solar Logic have expertise in design of low-energy (hence climate-sensitive) buildings. Taylor Oppenheim Architects undertakes projects such as research into energy use in buildings, post occupancy evaluations of a building's thermal performance and the development of guidelines and performance indicators for energy and environmental use in buildings.

Your Home (a joint initiative of government and industry) is a suite of guide materials developed to encourage the design of low energy homes. It includes a Home Consumer Guide directed at the general reader and a Technical Manual written for designers and builders. The consumer guide is currently available in Special State editions with climate specific information for New South Wales, Queensland and Victoria. The Technical Manual takes account of Australia's broad range of climatic conditions, providing different design strategies for each climate zone. The climate zones were defined by the Bureau of Meteorology.

Building Energy Rating Schemes

CSIRO Manufacturing and Infrastructure Technology are carrying out a major upgrade of the Nationwide House Energy Rating Scheme (NatHERS) software, which calculates energy ratings for residential buildings. Ratings are based on the amount of energy that would be needed to provide acceptable thermal conditions inside the building. The model assumes that building occupants will open the windows during warm weather, when ventilation would improve their thermal comfort. Among many other improvements, the model will now use a thermal sensation index to evaluate the building occupant’s thermal comfort. The modelling of building ventilation has been improved, and will use measured outdoor wind speed and direction.

Solar Logic owns and markets BERS, the Building Energy Rating Scheme. This scheme calculates the energy efficiency of a house in any Australian climate. Hourly climatic data for 28 Australian cities is used for the simulation of building thermal performance.

Environmental impacts of buildings

The construction and operation of cities is one of the most significant human activities contributing to global warming. The University of Tasmania’s School of Architecture is addressing the environmental impacts of buildings. A major international project in progress is the development of a Building Environment Rating System. This will assist designers and government authorities to improve the performance of buildings, thereby reducing their greenhouse gas emissions, their depletion of non-renewable resources and their emission of pollution to the biosphere.

Case study Melbourne City Council’s new administration building has been planned to respond to the well-known – and often lamented – vagaries of the Melbourne climate. Because of its situation on the southern edge of a warm continent, Melbourne’s spring and summer weather shows considerable dayto- day temperature variation: hot winds from the northern land mass tend to alternate with cool breezes off the Southern Ocean. There is also a significant temperature variation from day to night. The planned design responds to this variability by incorporating considerable heat storing materials – a huge tank of water and phase change materials. This heat store will stabilise temperatures inside the building. On hot days, cool water will be pumped through panels fixed to office ceilings, and the cooled air will sink down into the office space below. After midnight, when the air outside the building has cooled, warm air will be flushed out of the building and replaced by cooler outside air. An automatic weather station (AWS) installed on the building roof, together with links to Bureau of Meteorology AWSs upwind, will be used to automate the building’s response to weather fluctuations.

Building integrity/Natural hazards

Consulting engineers such as VIPAC (Vibration, pressure and acoustics) need to estimate wind forces on proposed structures, using scale models of buildings in wind tunnels to map likely wind forces across the structure. Initially, the forces on a proposed building are determined using a constant airflow in the tunnel. The actual wind forces for each wind direction are then estimated by scaling up the constant tunnel wind speed to actual observed speeds, using the Bureau of Meteorology’s historical climate data. The estimated wind forces are used in design to ensure the building’s structural integrity, in decisions about the placement of air exhausts and intakes and building cladding strength. Wind effects on pedestrians and the likely building deflection in strong winds are also estimated.

Scale model of buildings used in wind tunnel. (Courtesy of VIPAC Engineers and Scientists)

In 1999 Macquarie University’s NHRC completed production of PerilAUS I – a database focussed on natural perils including tropical cyclones, floods, bushfires, wind gusts, hail falls, tornadoes and landslides. As indicated in Figure 3.8, the built environment is more vulnerable to the impact of some perils than it is to others.

Figure 3.8 The contribution of each of nine natural perils to total building damage 1900-1999. Source: Risk Frontiers, Macquarie University.

The latest scheme (PerilAUS II) uses these data to develop relative risk ratings for each of the nine natural perils for each of the 2,573 postcodes in Australia. The map presented in Figure 3.9 provides one view of the spatial distribution of natural perils and relative risk on a postcode basis.

Figure 3.9 Natural hazards potential map based on nine hazards, 1=low, 5=high. Source: Risk Frontiers, Macquarie University.

Most Australians live in urban areas - more than 65 per cent live in five coastal cities. Extreme weather events such as floods, storm surge, severe winds and bushfires can threaten city dwellers’ lives and damage buildings and urban infrastructure. Natural hazards cannot be averted, but governments can reduce their impact by knowing the potential risk and recommending precautions, such as improved building codes.

Geoscience Australia is Australia’s national geoscience research organisation. Its Cities Project is researching a range of natural hazards and how they affect urban communities. Its overall objective is to facilitate safer and more sustainable Australian communities. In conjunction with the Bureau of Meteorology, assessments of risk from natural hazards have been carried out for Cairns, Gladstone and Mackay (Figure 3.10) and for south-eastern Queensland. A study of the risk from natural hazards in Perth is currently under way.

Figure 3.10 In this example from the Cities Project, the results of a multi-hazard risk assessment for Mackay compare the impacts of different hazards as a function of the return period in years. Source: Geoscience Australia

Water Use

One of the greatest challenges facing Australia is how to stop using more water, and to use what we have more efficiently. Water supplies per capita have fallen dramatically since 1970 and are set to continue declining, according to a United Nations report (UN 2003). In Australia, consumption of freshwater resources rose from 14 600 GL in 1983-4 to 23 300 GL in 1996-7. Irrigation increased by 30% between 1990 and 2000. Many solutions have been canvassed, including water trading and more efficient irrigation methods.

Accurate evapotranspiration data are necessary to estimate soil dryness, hence irrigation requirements. Fine-tuning the use of irrigation water maximises agricultural yields, while guarding against exacerbating soil salinity caused by rising water tables. The Bureau of Meteorology’s South Australian Regional Office is continuing work on a project to estimate potential evapotranspiration from satellite-derived solar radiation data and surface observations made at AWSs. On completion of the project, it will be possible to estimate evapotranspiration in near real time at any Australian location.

A national workshop was convened by the National Program for Irrigation Research and Development (NPIRD) to establish the need for national standards for irrigated crop water balance and crop evapotranspiration field methodologies. The findings of the workshop showed that there is agreement on the need for national standards that will enable comparison of outputs from different districts and enable the Bureau of Meteorology to more effectively fulfill its role as a national service provider by providing client focused information using a common methodology.

In response to requests for information about the hydrologic impacts of the recent bushfires in Victoria, New South Wales and the ACT, the CRC for Catchment Hydrology has established a website to deliver information useful to catchment and water supply managers. The site is online at http://www.catchment.crc.org.au/bushfires.

In March each year the Bureau of Meteorology’s Western Australian Regional Office issues statements to agricultural and water agencies regarding the prospects for rainfall in the south-west of Western Australia over the May to October period. A preliminary statement is issued to the water agencies the previous September or October, to assist in water management decisions over the summer months. The statements are based on work done by the Western Australian Regional Office linking rainfall in south-west Western Australia to interannual changes in the Southern Oscillation Index (Tapp 1997).

Sydney Water runs Streamwatch - a community environmental education and action program. The aim of the project is to empower the community to protect the health of their waterways by using water quality monitoring as a tool. Several hundred schools, community groups and local government bodies carry out water quality testing every week at their chosen sites around the Sydney area and load the resulting data online. The Bureau of Meteorology’s New South Wales Regional Office has provided rainfall data to be used in the on-line information. Once the water quality data are correlated against rainfall, the dataset will become significantly more useful.

In many communities, much of their limited water supply is used to provide evaporative air-conditioning during hot weather. For example during a three week period during early 2003 in Cobar, the maximum temperature did not drop below 40 degrees Celsius. Even with water restrictions, the town used a million litres of water a day on air-conditioning. At this rate of usage, the town's water supply was predicted to run out by June 2003.