RP1024: Informing the Next Generation Residential Energy Assessment Tools.

Building on the existing NatHERS platform, the project develops the next generation of house energy rating tools capable of assessing a wider range of energy and carbon impacts, providing the housing industry with high quality design feedback and accurate performance assessments. The project greatly extends and improves the functionality of existing tools to reward the use of high performance technologies and construction systems, and the integration of renewable energy systems.

Developed from a strong evidence-base and validated in all key Australian climates, with a particular emphasis on improving the knowledge base from subtropical and tropical climates, this project provides one of the fundamental building blocks required by industry to continue along the pathway to low carbon housing.

The project supports industry activities to design, construct and deliver affordable, thermally comfortable, energy efficient low carbon homes that meet the needs of households. The designers, builders, building product and appliance suppliers, assessors and households will have world class design tools, built on a foundation of exceptional science, and validated for Australian housing typology and climatic conditions. Building regulators will have a strong evidence base in establishing the environmental, economic and social costs and benefits of low carbon homes.

The end goal of this integrative project is a housing industry capable of producing thermally comfortable economically viable low carbon homes with integrated solar systems, and testing compliance to lower carbon regulatory standards.

Program

Program 1: Integrated Building Systems

Project leader

Prof Wasim Saman, UniSA

Project status

Complete

Project period

09/2015 to 06/2019

Publications
Media
Partners

_{Peer Reviewed Research Publications}

RP1024: Journal Article: Evaluation of a whole-house energy simulation tool against measured data

Whole building simulation tools can play a significant role in energy savings through building design and operation, implementing building energy rating schemes, and demonstrating compliance with building energy codes. It is critical that any development of a tool be properly evaluated by state-of-the-art evaluation techniques. Using the collected data of more than forty houses in three Australian cities (Adelaide, Brisbane and Melbourne) through monitoring and survey, this study evaluates the Chenath engine and the AusZEH design tool against actual electricity consumptions under realistic conditions. The Chenath engine simulates space heating and cooling, and the AusZEH design tool simulates whole-house operation.

The results show, on average, that the predicted space heating and cooling electricity consumption agrees with the monitored data with an R-squared value of 63.8% and 64.6% respectively; the predicted total electricity consumption agrees with the observed data with an R-squared value of 84.2%; and the predicted whole-house electricity consumption is 11.8% lower than average actual electricity consumption. It also demonstrates that the AusZEH design tool can simulate the average daily electricity consumption patterns for each season, and for sub-grouped electricity consumption for space heating and cooling, water heating, lighting and other appliances. This reasonable agreement provides the users with confidence in the performance of the Chenath engine and the AusZEH design tool.

Read the full article here: https://doi.org/10.1016/j.enbuild.2018.04.034

RP1024: Conference Paper: Investigating equivalence in compliance pathways to Australian housing energy efficiency

Current regulatory pathways to compliance in energy efficiency for Australian housing are via provisions in the National Construction Code (NCC). This paper first identifies performance evaluation criteria set out in the code presented as a comparative analysis across the different methods of achieving compliance. Jurisdictional and concessional variations are discussed and thereafter an examination of the effect of specific design and location factors that impact the commonly used deemed to satisfy route to compliance.

A study is presented in the paper investigating typical South Australian temperate climate housing styles in terms of their expected energy performance and compliance. This is done to test for measurable differences or test where equivalence can be shown to be reasonably achieved. This study highlights the issue of alternative pathways, being different options of using software modelling or elemental compliance based on specification details. The sample set is a modest seven houses only but carefully chosen to show the compliance pathway results for different options across this sample set. Further measures of house energy performance evaluation and comparison are drawn from the literature.

Conference paper from the 52nd International Conference of the Architectural Science Association (ANZAScA) 28 Nov - 1 Dec 2018, Melbourne, Australia.

Investigating equivalence in compliance pathways to Australian housing energy efficiency (1192582 PDF)

RP1024: Journal Article: Modelling study of the impact of thermal comfort criteria on housing energy use in Australia

It is an increasing challenge for building designers in the 21st century to provide for thermal comfort at minimum energy cost by taking into consideration both the current and the future warming climate. Most previous studies have focused on thermal comfort in non-residential buildings under current climatic conditions. This study evaluates the impact of thermal comfort criteria by lowering the acceptability limits on space cooling energy requirements for Australian residential buildings, under both the current and projected future climates (with an assumed global warming of 2 °C) through building simulations using three different types of typical building constructions – lightweight, heavyweight, and a combination.

Read the article here: https://doi.org/10.1016/j.apenergy.2017.10.110

RP1024: Conference Paper: What the Indoor Air Temperatures in Houses in Three Australian Cities Tell Us

This study analysed over 1.8 million measurements of air conditioner power consumption and indoor/outdoor air temperatures in 129 houses in Adelaide, Brisbane and Melbourne from 2012 to 2014. It was found that the preferred indoor air temperature range, at which occupants are most unlikely to operate air conditioners, increases for warmer local climates.

rp1024 indoor air temperatures (1509427 PDF)

_{CRCLCL Project Reports}

RP1024: Final Report: Informing the Next Generation Residential Energy Assessment Tools

The Nationwide House Energy Rating Scheme, commonly known as NatHERS, which is applied through software tools such as AccuRate Sustainability, has become the predominant pathway for complying with energy efficiency requirements within the National Construction Code of Australia.

Current energy efficiency regulations have remained unchanged for a decade and there is an intention to increase these requirements, through mandating a higher minimum star rating for buildings. Furthermore, existing energy efficiency regulations only cover the building envelope, through the energy needed for space heating and cooling, and not the energy efficiency of major appliances. In addition, current regulations do not incorporate sufficient quality assurance processes, in relation to compliance. Finally, the current regime is inconsistent with international best practice.

This project aimed to review, analyse and recommend changes, in light of these issues. One conculsion being that whilst the original context of NatHERS was to reduce greenhouse gas emissions the rapid transition to renewable energy underway in the Australian energy system, makes this context is no longer valid.

Informing the Next Generation Residential Energy Assessment Tools (8116314 PDF)

_{News article}

UniSA Media Release: Launch of RP1024 NextGen Ratings Tool project

29 September 2016

Hayley Byford & Alicia Hage

The CRC for Low Carbon Living in association with project partners CSIRO, Energy Inspection, and the University of South Australia launched the RP1024 NextGen Rating Tools project in Adelaide on 29 September 2016. The project launch was hosted by the Research Node for Low Carbon Living, based at the University of South Australia.

UniSA’s Professor Wasim Saman, the Project Leader, was delighted that so many guests from industry and government braved the stormy Adelaide weather to attend the event. The launch gave stakeholders an insight into the project and an opportunity to provide feedback on the project objectives and expected outcomes.

Scientia Professor Deo Prasad, CEO CRC Low Carbon Living, stated “We measure our success by the impact we make; we plan to move forward with the best research, and the CRCLCL believes it’s important to look at a better rating tool”

These new tools will revolutionise the building industry by enabling designers, builders and homeowners to evaluate all of the major energy consuming activities within the home, delivering a comprehensive understanding of energy usage and how to reduce it. The project, RP1024 NextGen House Energy Design Tools, will be undertaken over the next two years and will help provide one of the fundamental building blocks for low carbon living.

Project Leader Professor Wasim Saman says that it is crucial to develop a national rating tool that will help build comfortable and high performance houses. “These homes will be still there in another 50 years or more and if we don’t build them correctly now we will have issues – particularly with climate change,” he says.

In addition to causing less environmental damage, low carbon houses give homeowners greater comfort, reducing the amount of heating and cooling required and the associated costs. CRCLCL Program 3 Leader (Engaged Communities) Dr Stephen White says better house energy ratings will help consumers and home designers create comfortable, healthy and affordable homes. “In addition to saving on energy bills for heating and cooling, an energy efficient house will be naturally warm in winter and cool in summer – a highly efficient home may not even need an air-conditioner,” he says. “Energy rating tools enable builders to do sensitivity analysis around the house design elements, insulation, window placement and type, shading, materials of construction etcetera, to find the lowest cost way of achieving thermal comfort.”

Chief Executive Officer of Energy Inspection Bryn Dellar says that these new tools will also warn potential buyers or lessees of the energy efficiency of a house. “You can’t tell by looking at a house how efficient it is, so if you’re buying a house or want to lease a house, it should be rated – so it’s about disclosure,” he says. “Low carbon housing is important because of the emissions produced and the potential impacts on climate change and we know there is a broader economic benefit in avoiding dangerous climate change.”

The current rating tool was first developed in the 1980s and hasn’t been updated for more than a decade, and according to Prof Saman, is based on assumptions that have changed. “People use their houses differently and build their houses differently now – so we are updating all of the assumptions made in the tool and basing them on real evidence from evaluation and monitoring results that we have obtained,” he says. “The current tools only concentrate on the building envelope, in other words the walls, floor and the roof, so we are going to make the new tool include all the major energy using activities within the home, including the hot water, the appliances and the lighting and the air-conditioning system, and that will make it more comprehensive. We have got clear evidence through some real housing development evaluations that this actually works, if we correctly use the rating tool, there are lots of benefits which we have the evidence – and we are going to use this evidence in building the new tool.”

According to a report from the Australian Sustainable Built Environment Council (ASBEC) buildings are responsible for a large portion of emissions in Australia. If house emissions can’t be effectively measured then they are difficult to effectively manage so it is essential for new tools to be developed and integrated into common practice so consumers begin to seek out more energy and carbon efficient homes. “This will drive a market for better quality homes, that better meet the aspirations of home owners, and create new jobs,” Dr White says.

Low carbon living research is vital and this project, funded by the CRC for Low Carbon Living, with industry partners CSIRO and Energy Inspection, follows action being taken in the United Kingdom, Europe, the United States of America and other developed countries to achieve low carbon homes.