September 2024

Sustainable Schools: Net Zero Buildings

Calls to limit global warming and climate change by making human activity, products, and processes more resource efficient, and to reduce greenhouse gas emissions are increasingly strident. Gases like methane, chlorofluorocarbons, and carbon dioxide (CO2) are the chief culprits. CO2 from burning fossil fuels, biomass, and industrial processes contributes to over 70% of GHG emissions.

In response, many governments want to phase out fossil fuel use, transition to renewable energy sources and thereby reduce CO2 or CO2 equivalent emissions. In 2015, 190 nations signed the Paris Accords. As part of this agreement, signatories pledged to restrict global warming to no more than 1.5°C, as recommended by scientists.

Since then, countries, the government sector, NGOs, industries, and individuals have set goals to reduce GHG emissions (especially carbon emissions) and energy consumption. France, New Zealand, and the UK to become net zero emitters of carbon dioxide or CO2 equivalents by 2050, ensuring that government policies align with this objective. In 2022, Australia followed suit, committing to cutting emissions by 43% by 2030, and becoming a net zero economy by 2050.

Despite these good intentions, carbon emissions are still on the rise. In 2019, global CO2 emissions related to energy consumption peaked at 33 gigatons, over 11 times the amount recorded in 1900. According to the Australian Department of Industry, increased energy use in the residential sector will lead to soaring emissions.

Enter the concept of net zero energy buildings which will significantly transform current practice within the construction industry, if widely adopted.

Principles of Net Zero Energy Building and Passive Design

It’s a fact universally acknowledged that there are as many definitions of Net Zero Energy and Net Zero Energy Buildings (NZEBs) as there are countries. Crucially, Net Zero doesn’t mean eliminating all GHG emissions. The core principle behind Net Zero is that you make up for emissions by offsetting same quantity of emissions elsewhere onsite.

To simplify:

• NZEBs are buildings where the total amount of energy used onsite is equal to the amount of renewable energy created or purchased offsite.
• Their overarching objective is to emit fewer GHG emissions during operations compared to traditional builds.
• NZEBs can sometimes consume non-renewable energy and produce GHG emissions, provided this is balanced out by minimising energy consumption and using renewables where possible.
• NZEBs typically incorporate Passive Design or Passive House features in the building envelope[1] which work in conjunction with renewable energy sources like the sun or the wind. This maximises heat conservation and a building’s thermal efficiency to ensure natural ventilation and heat don’t escape. This is a “fabric first” approach.
• Passive design features are high-efficiency, energy-saving components such as extra insulation, window glazing, heat pumps for heating or cooling needs, skylights to provide natural light and heat, LED lighting (which is more efficient than fluorescent lighting,) passive solar gain in winter, shading in summer, and natural ventilation.
• Both passive and NZEB design pay attention to details such as building orientation, thermal mass, airtightness, and preventing unwanted heat gain or loss. Both designs focus on minimising the need for large external HVAC appliances which increase energy consumption and emissions.
• Finally, NZEBs typically harness and reuse energy from devices e.g. using refrigerator exhausts to heat hot water dispensers. NZEBs make use of heat energy that would otherwise be wasted.

[1] A building envelope is the physical barrier between the conditioned and unconditioned environment of a structure, including resistance to the transfer of noise, water, heat, light, and air. The envelope includes all components of a building’s outer shell which keep temperatures consistent in heated, dry, or cooled indoor spaces and make climate control easier.

Why Schools Choose Net Zero/Passive Design

 It’s a good idea to invest in NZEBs because:

High energy consumption and environmental footprint: Most schools have lots of buildings and infrastructure. The construction and operational energy use of houses, offices, and schools makes up about 38 to 40 percent of GHG emissions whilst 40% of global energy consumption is attributed to buildings. The Australian school system is the fifth largest producer of carbon dioxide and carbon dioxide equivalent (CO2e) in Australia, based on energy consumption alone.

At many schools, appliances are on standby out of school hours

Fifteen schools located in Perth participated in a two-year Low Carbon Schools Pilot Program (LCSPP), from 2015 to 2017. Most participants adopted a “switch-off protocol” by late 2015. This meant turning off all energy consuming devices, including HVAC appliances like gas heaters, as well as hot water urns, refrigerators, lighting, printers, and computers at the end of each day. On average schools cut their total energy consumption by 12% between 2014 and 2017.

 Schools decreased energy consumption during the two-week October holiday by 28%. Between 2014 and 2017, nine of the 15 schools lowered their energy consumption, whilst four increased it. However, rising consumptions were partly due to other factors, such as increased enrolments. Electricity use accounted for most schools’ carbon emissions. Hence those whose total carbon emissions decreased by 15% or more were those that significantly reduced electricity consumption as well.

PV (photovoltaic) solar panels are ideal for schools

To be effective, this net zero technology requires large amounts of roof space to accommodate solar panel arrays. To generate power for large buildings, several arrays may be needed, and many schools have roof space for them. Furthermore, most of a school’s energy needs are met during daylight hours. As demand for renewables increases, PV panels are more affordable than ever before!

Having NZEBs on school grounds can raise your school’s profile. Investing in these buildings is proof of an environmentally conscious ethos. This is also in line with the widespread rollout of NZEB technology in Australia’s residential and commercial sectors.

NZEBs educate and empower school communities  

NZEBs can provide opportunities for learning about high-demand and developing industry sectors. Job opportunities in STEM fields are relevant here. Having NZEBs contextualises learning about the impact of human activity on the environment, making learning more relevant. It provides students with an opportunity to understand how knowledge and behavioural habits play out in real-world scenarios.

Students, staff, and the wider community feel less powerless in the face of serious global issues like climate change when they choose to make impactful changes like investing in net zero technology.

Learning opportunities can be aligned with curriculum subjects. For example, students involved in measuring resource use can learn how different metrics can help us understand our environmental footprint and why, as well as how to interpret and apply data in different contexts, for different purposes.

Drawbacks of Net Zero Infrastructure in Schools

Upfront costs for retrofitting and building NZEBs are higher than for conventional structures. Moreover, obtaining energy audits, installation quotes, and consulting experts to manage energy consumption and carbon reduction can be pricey. Schools with tight budgets may find it challenging to pay for increased costs.

Often NZEBs have higher embodied carbon then traditional builds – this must be addressed in future years.

Students, teachers, and staff need to constantly upskill to keep abreast of new NZEB technology and developments, to maintain facilities and keep them in good working order. Providing training and learning new skills requires time and money from schools and participants.

Processes to obtain permissions for and approval of new technology from government departments can be lengthy, compared to traditional builds which are familiar territory. One school in the Low Carbon Schools Pilot Program waited for nearly two years to get permission to install solar panels.

Consider the limitations of current NZEB infrastructure – buildings of four or more floors are unsuited to current NZEB technology, and generally cost more to retrofit.

Renewable energy sources may be unavailable depending on weather patterns. You may be able to store energy for use on cloudy days, at nights, or when there is no wind.

Schools with limited space for large structures and new technology may have to rely on batteries and obtaining renewable energy from the grid.

Older schools may need to significantly upgrade main switches and electricity stations before commencing work on NZEBs.

Savings aren’t always reflected in energy prices as the cost of energy increases. Tariffs vary between energy retailers. It pays to be a wheeler dealer who can effectively haggle if you want the best possible deal for your school.

Transitioning To Net Zero: What To Keep in Mind

What steps can schools take to make measuring resource consumption and transition to net zero energy easier?  What must stakeholders keep in mind?

• What metric is best to measure energy consumption? Arguably, measuring carbon emissions, energy costs, and resource use per student is more useful than measuring electricity consumption per square metre as is common within the energy industry. The per student metric provides schools with relevant, useful data and makes comparing schools easier.
• NB: Tracking carbon emissions in relation to building lifecycles and the amount of embodied carbon used in construction processes is tricky. It’s easier to start tracking resources by monitoring utility bills – i.e. water, electricity, gas. It’s vital to get a clear picture of your environmental footprint before transitioning to net zero. This first step provides a holistic picture of where schools can make changes to become more eco-friendly. Carrying out audits assists with this.
• Audits can also have unexpected benefits. They can identify unusual consumption patterns which can be changed by new policies and/or behaviour reminders. These may be due to leaks, faulty equipment, or wasteful consumption habits.
• Comparing audit results with other institutions helps schools become familiar with what typical or expected consumption patterns look like.
• Bundling upgrades that complement each other often works out cheaper than upgrading a single feature which saves time and money in the long run.
• Fundraise with other schools to achieve shared goals like solar panel installations. Connect with them to anticipate and solve challenges. Examine problems faced by institutions with similar sustainability/NZEB-related objectives, of similar sizes, and with similar student and staff demographics.
• Get involved in government programs which offer auditing services and advice to help your school transition to net zero. These initiatives can provide information about topics like:

1. net zero certification, sustainable product ratings
2. getting works authorised/approved by relevant departments
3. applying for grants and schemes, engaging with eco-friendly suppliers
4. operating net zero technology on school grounds.

As with the Low Carbon Schools Pilot Program, initiatives may offer discounted services like energy audits or even technology to participants.

• Thinking of buildings as integrated systems and upgrading all features simultaneously minimises the risk of finding that newer features don’t work with older ones.
• Offsetting carbon emissions and non-renewable energy use isn’t a sure thing. For example, planting trees becomes null and void when a fire destroys your forest and carbon is released back into the atmosphere – planned offset actions don’t always work out as planned and may worsen carbon emissions in certain situations.

Monitoring and making large-scale infrastructure changes to schools, lowering energy consumption levels and carbon emissions may be challenging, but even without transitioning to NZEB technology, you can make a difference. After all, 70% of sustainability actions identified in the 2015-2017 Low Carbon Schools Program were zero or low-cost.

Monitor and plan for new infrastructure carefully. Consider value for money and use experienced suppliers that you have heard great things about from other schools. Bundle upgrades to get cheaper deals. Don’t rush your transition – do your research to find the right fit for you in terms of technologies, suppliers, and value. Happy transition to Net Zero!

Bibliography

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Author
Estelle Borrey
PhD in European Languages and Cultures.