Appropriate window coverings can provide enormous benefits to the energy efficiency and comfort of our homes. Indoor blinds can create an insulating layer of air inside the glass to retain heat in winter, or provide a shading effect which reduces solar heat gain during summer.

High quality cellular indoor blinds can provide a lot of advantages. Their unique honeycomb structure traps air, enhancing their insulation properties to better regulate indoor temperatures with lower heat loss (or gain).

Exemplary Energy’s consulting team has been engaged by one of the major suppliers of cellular blinds to model and assess the energy performance benefits of a home that has windows furnished with a range of blinds.

We have selected a design from the publicly available set of de facto standard designs used for interpreting the impacts of construction changes as modelled by house energy rating software packages in the Nationwide House Energy Rating Scheme (NatHERS) which assume the poorly performing light-coloured Holland blinds in rating mode. The house was modelled with NCC-compliant Deemed to Satisfy (DTS) ceiling, wall and floor insulation, concrete slab-on-ground floors, brick veneer external walls and plasterboard internal partitions, and (separately) a 6-star version – between them, these broadly reflect the energy efficiency of homes built in recent years. For each of these, two types of window were modelled: a clear single pane glass commonly used with standard aluminium frames and also a generic double-glazed window with thermally enhanced aluminium frames.

For each of the four configurations, the heating and cooling energy demand of the home was calculated assuming the standard NatHERS occupancy of a 4-person household using the 2023 version of the NatHERS software.¹

We applied the results (energy consumption) to a gas central heating system model which assumes a system efficiency of 61%, and (again, separately) to a heat pump space heater with a coefficient of performance (COP) for heating of 3.7 and COP for cooling of 3.3.

Scope 1, 2 and 3 greenhouse gas emissions were estimated using the emissions factors published in the Australian National Greenhouse Accounts Factors: 2023.

Results from previous work suggest that heating savings of up to 50% (compared to a 6-star baseline home in Sydney) might be feasible with the highest performing products.

We look forward to bringing you more details of our findings in a future edition of this blog.

Notes:
1. This occupancy is known to overestimate the energy consumption of the average household so our report will include commentary on the likely impact for real families.

Efforts to improve energy efficiency and reduce carbon emissions are driving substantial change across most parts of the economy. One major part of this shift is the move away from fossil gas which, in Victoria, is responsible for around 17% of the state’s greenhouse emissions.

A significant component of gas demand comes from water heating. Domestic hot water is responsible for about 30% of residential energy use along with a large proportion of energy used in commercial and industrial operations.

A rapidly growing cohort of households is looking to play their part in this – while saving money – by shifting their water heating from gas to electricity. In many cases, this means switching to a heat pump water heater.

It is likely no surprise to readers of this blog that heat pump water heaters use the same technology as your refrigerator or air-conditioner, applying a thermodynamic ‘trick’ to produce more heat – typically about 3 or 400% more – than the energy fed into them.

While they can be fantastically efficient, recent criticisms have noted a range of risks, challenges and conflicting debates about the quality, reliability and durability of the products that are being installed.

Governments have an important role to play here: their usual responsibilities for consumer protection are compounded by policy interventions urging more, and more rapid, uptake of heat pump technologies.

Again in Victoria, one of those policy interventions is the Victorian Energy Upgrades (VEU) scheme. The VEU rules refer to various Australian Standards and set minimum quality and performance benchmarks for products to be included in the scheme. Products are required to meet Standards for design and construction¹ which specify a range of performance-based requirements, and are required undergo laboratory testing to determine the energy performance of some components^2,3 along with modelling to determine the overall performance of the product under various loads in different environments⁴.

However, policymakers have been concerned that the existing Standards and requirements may not be sufficient to ensure that products offered under the program are of sufficiently high quality to provide the durability and longevity that consumers expect. Incentivising poor-quality products would present a risk to the reputation of the technology, a lowering of consumer confidence, reputational risks to the VEU scheme, and could delay the electrification of Victorian households or present additional challenges to Victoria meeting its emissions reduction targets.

For these reasons the Victorian Government Department of Energy, Environment and Climate Action (DEECA) has engaged Exemplary Energy to review evidence and better quantify the extent of challenges to the VEU scheme relating to heat pump water heater quality in order to inform recommendations about future changes to the VEU rules. We have assembled an expert team which includes our Directors Trevor Lee and Dave Ferrari, Staff Coordinator Jean Tan, Ken Guthrie (the former Chair of the International Energy Agency’s Solar Heating and Cooling Program and ISO Standards Committee on Solar Energy), and Graham Morrison (Emeritus Professor of Engineering at UNSW).

The project will involve undertaking an international review of requirements in other jurisdictions and engaging with product manufacturers to understand best practices in the market. With this in hand, we will review the current VEU scheme requirements and seek to identify any gaps.

Our insights will help to better quantify the threats and challenges in this part of the energy transition, producing better outcomes for manufacturers, policymakers and consumers alike.

Notes
1. AS/NZS 2712 Solar and heat pump water heaters — Design and construction
2. AS/NZS 5125 Heat pump water heaters — Performance assessment
3. AS/NZS 4692 Electric water heaters, Part 1: Energy consumption, performance and general requirements
4. AS/NZS 4234 Heated water systems — Calculation of energy consumption

This year’s Asia-Pacific Solar Research Conference (APSRC) was hosted by RMIT in Melbourne 5-7 December 2023 celebrating its 10th anniversary. A review of the event and the innovations and consolidations presented there will follow early in the New Year. In the interim, here is a summary of how Exemplary Energy participated in this annual event.

Exemplary Energy presented three oral papers, sponsored or co-sponsored three awards, and hosted a table at the conference dinner.

Our oral papers were titled:

• Mandatory disclosure of residential energy efficiency ratings in the ACT (presentation here)
  This paper presented a summary of two decades of data on the relationship between energy star ratings and sale prices of ACT real estate under Australia’s only mandatory disclosure program
• Enhancing Australia’s weather and climate data for bench-marking simulations (presentation here)
  Outlining the recent improvements to Exemplary’s weather and climate data and tools available in our latest data update
• Adapting reference periods for building simulation climate data in a changing climate (presentation here)
  A review and analysis of options for applying shorter basis periods in defining climate norms (Reference Meteorological Year – RMY – datasets) to better account for the impacts of a changing climate

We also supported three awards to the finest student researchers based on the quality of the extended abstract and the oral presentation or poster by:

• Co-funding the Wal Read Memorial Award for Best Student Poster, awarded to Yansong Wang of UNSW for the poster Multi-Junction GaAs Photodiode Arrays for Biomedical Applications
• Sponsoring the John Ballinger Award for Best Buildings-related Student Poster or Presentation, awarded to Tharushi Samarasinghalage of RMIT for the oral paper Multi-objective optimization of BIPV envelope design: BIPV Cladding application; and
• Sponsoring the Monica Oliphant Prize for Best Female Student Poster, awarded to Haoran Wang of UNSW for her paper Effects of Soldering Flux on the reliability of TOPCon and HJT Solar Cells

The full range of recipients have been listed on the APSRC website.

Exemplary Energy congratulates all the recipients of the APSRC 2023 awards, and wishes them all the very best in their research endeavours.