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How HVAC can step up to a net zero world

Data centres sharing waste heat with the next-door swimming pool, super efficient facades, renewables, storage, phase-change materials, solar cooling, natural ventilation and personalised comfort control. Welcome to the future of net zero HVAC as predicted by experts.

The path to net zero commercial buildings is on the tip of the industry’s tongue, and will require changes to building construction techniques, materials and technologies.

A key building technology in need of transformation, currently responsible for about 40 per cent of a building’s energy use, is heating, ventilation and airconditioning (HVAC).

With this in mind, the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH) has released a new report into the future of HVAC in the context of a net zero world, based on a foresighting workshop held last year with industry experts, facilitated by Dr Paul Bannister.

The question to answer: “How can our energy-intensive approach to HVAC in buildings be further developed, refined and changed to help deliver the net-zero buildings of the future?”

Buildings will change

To understand what HVAC might look like, it is important to conceptualise what buildings themselves will look like, with the workshop agreeing that passive design and climate appropriate architecture will re-assert themselves as dominant design drivers.

“Buildings will be more modular and flexible, integrated and automated,” the report says. “They will be built with better materials; phase change and thermal storage will be normal, and all building envelopes will be thermally efficient and well-sealed.”

Buildings will also become energy generators and energy storage infrastructure.

Technologies that will help reduce HVAC consumption include smart facades, better building sealing, building-integrated photovoltaics, batteries and energy storage, and phase-change materials to stabilise building temperatures.

Renewable powered and efficient

HVAC systems will be powered by renewable energy, battery storage, and thermal storage.

Ventilation systems will also be key to the net zero goal.

“Ventilation is key in net-zero buildings and natural cross ventilation, hybrid ventilation, ventilative cooling and evaporative cooling all have roles to play. Refrigerant based systems will be efficient and low GWP [global warming potential] but alternatives to vapour compression refrigeration will also be common.”

Solar cooling, natural and mixed-mode ventilation systems, non-vapour compression chillers, seawater cooling and heat recovery technology will also be part of the solution.

The importance of planning

The report says town planning will play a greater role in ensuring net zero buildings, as we begin to see buildings less as discrete entities but ones that fit into their surrounding neighbourhood.

For instance, waste heat from one development could be used in another.

“A practical example would be planning a swimming pool next to a data centre. Multi-use developments can provide greater ability to utilise waste heat due to simultaneous heating and cooling requirements.”

Solar access will also become a growing issue, as sunlight demands grow for on-site solar.

As such the approaches and objectives of planners may need to shift.

Occupants to undergo significant cultural change

While HVAC too will become more efficient, it will also become more targeted to occupant need.

Occupants of net zero buildings themselves will have “undergone a significant culture change”, shifting their expectations of HVAC due to a better understanding of comfort and indoor environment quality.

“Occupant behaviours will also be different, dressing for the climate and with a better understanding of individual comfort preferences and the energy/cost/emission implications of individual choices.”

Building regulations will need to be performance based

Regulations will need to be performance based, specifying maximum heating and cooling loads in order to drive better building performance, the report says.

“Regulations will require all buildings to meet minimum natural ventilation capabilities and free running performance requirements, to incorporate waste heat recovery, and incorporate rainwater harvesting and waste-water management provisions.

“Zero net CO2 equivalent will be the overriding performance requirement. Compliance will be mandatory, verification will be strict and will extend beyond the design and construction phases into the operational phase of the building and across its full operating life.”

Helping meet future challenges

AIRAH chief executive Tony Gleeson said foresight activities could help the industry navigate change by providing early warning of barriers and opportunities, and provided evidence for government policymakers.

“By tasking a group of experts and practitioners to develop a credible picture of future buildings and HVAC, AIRAH has been able to start the conversation on the strategies that can be used, and the changes to industry, technology and practice that will be required to make this happen,” he said.

In summary, the report said for net zero buildings to become a reality:

  • Buildings must become more energy efficient and more energy productive. This includes higher standards for fabric thermal performance and building sealing, as well as performance benchmarks for ongoing operation and maintenance.
  • HVAC systems must be designed, installed, operated and maintained for high efficiency and low emissions. Measurement, monitoring and ongoing maintenance is the key to improving energy efficiency and productivity of existing HVAC systems.
  • The energy used to run high-efficiency HVAC&R in highly efficient buildings must come from a clean low-carbon source.
  • The relationship between buildings and building occupants must change to become more flexible and interactive – in both directions – than it is at present.
  • Governments and HVAC industry stakeholders must commit to the net-zero buildings goal by implementing a range of supporting data, information, training and education measures to enable informed consumer choice, innovation, commercialisation and deployment of new technologies and business models.

The paper calls for training and education, including the development of a net-zero building retrofit tool and behaviour change programs; increased research into low-emission HVAC and better support for innovative technology and approaches; and increased investment in Australian research for Australian innovations in HVAC to counteract industry “conservatism”.

“Government and industry should support innovation and commercialisation of low-emission HVAC technologies by supporting demonstration projects.”

AIRAH’s Phil Wilkinson said the peak body would continue to lead change through the implementation of the “PRIME whole-of-HVAC&R industry strategy for the transition to low emissions”.

The IHub for Affordable Heating and Cooling could be on the way

“AIRAH is working with the CSIRO and PRIME to establish an Innovation Hub for Affordable Heating and Cooling, or iHub. And of course, the Institute will continue to advocate for energy policy changes to incentivise the design and delivery of net-zero buildings and low-emission HVAC.”

The Fifth Estate will discuss technologies for net zero buildings at its Visit Tomorrowland event on 19 September in Sydney.

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