Affordable DIY Retrofits for Rapid Decarbonisation and 21st Century Warming
J.J. Shiel, B. Moghtaderi, R. Aynsley, A. Page, J.M. Clarke
Organisation of Presenter:
University of Newcastle; & EnviroSustain, Australia
Australia has one of the world’s worst-performing building stocks but has recently committed to zero carbon by 2050 at the 2015 Paris COP 21 talks. This research shows how to rapidly decarbonise the operational emissions of the existing housing stock in Australia’s Warm Temperate climates by finding convenient and affordable retrofits for which a householder can “do-it-it-yourself” (DIY), according to how much money they wish to spend (Renters, Owners and Energy-positive). The retrofits suit the most common house constructions to take advantage of passive solar and the exergy principles of utilising low quality energy for heating and cooling wherever possible.
A study was carried out of cost-effective retrofits of typical Australian housing in Adelaide, which has a Warm Temperate climate, to reduce the heating and cooling greenhouse gas (GHG), or carbon equivalent, emissions. Two scenarios in 2050 were investigated using the CSIRO’s Australian Climate Futures (ACF) web-based tool which facilitates objective selection of individual representative models according to the requirements of particular studies, and is based on the IPCC’s latest Fifth Assessment Report (AR5): Extreme Climate Change, corresponding to Representative Concentration Pathway (RCP) 8.5; and a Scarce Resources scenario corresponding to RCP 4.5.
The 2050 Adelaide hourly weather profile was calculated using Belcher’s technique which is a “morphing” approach which uses 1) a base set of hourly weather parameters and 2) the changes projected of the main weather parameters by a general circulation model (GCM). For this study, the HadGEM2-ES model was identified as a suitable representative of both scenarios, using the ACF tool.
Common Australian housing construction types were modelled with the AccuRate Home Energy Rating System (HERS) program e.g. with heavy, medium and light-weight walls, and timber and concrete floors. Simulations were conducted of energy saved by various combinations of retrofits, for the base climate today and for the two 2050 scenarios. These energy savings were converted to GHG savings using the GHG efficiency of ducted air-conditioning, using the GHG efficiency of South Australian electricity generation.
A method is also provided to estimate the size of photovoltaic system for a house to ensure zero net emissions, after improving the efficiency of services and appliances, along with any changes required in occupant behaviour.
In general, the key decarbonisation strategies are to carry out the deepest retrofits on infrastructure 1) with the greatest longevity; 2) in the best condition; 3) located 20m above sea level; 4) that use large operational GHG emissions; 5) are near public transport; and 6) are located in regions with the highest electricity carbon intensities e.g. in Victoria and NSW/ACT.
For Warm Temperate region housing retrofits, we show there are large carbon savings to be made for older housing constructions of predominantly light-weight and heavy-weight houses with timber floors. The most affordable and effective carbon retrofits were a) reducing the living rooms size by partitioning; b) increasing the insulation of the perimeter (ceilings, roof, floor & walls-cavity & cladding), including with shading with PV panels, changing colours, using “cool” paints or vegetation and adding carpet; c) adding thermal mass particularly to lower air-conditioning usage; d) improving infiltration to an optimum level; e) improving air speeds with ceiling fans; and e) changing the window solar gain with e-films.