Going Carbon Zero – Building Services Specifics
September 2, 2020 By Anthony Broatch
Overview
This article gives insight into what carbon zero refers to and provides advice on making new and existing buildings carbon zero.
The Basics
What is a Carbon Zero Building?
The WorldGBC defines a net zero carbon (carbon zero) building as a building that is highly energy efficient and fully powered from renewable energy sources (on-site and/or off-site). Carbon offset programmes also exist to cancel out any unavoidable emissions generated. Embodied carbon which is considered the carbon emissions from the materials used in production, construction, and end of life are currently not counted towards carbon zero status.
What is Carbon?
The term carbon in this context, short for carbon dioxide, refers to all greenhouse gases not just carbon dioxide. The reason the word carbon is used is because carbon dioxide forms the majority of the greenhouse gases released.
Why are Carbon Emissions Bad and Why Should I Care?
Carbon dioxide and other greenhouse gases in the atmosphere regulate the earth’s surface temperature by reflecting energy back to the earth, effectively trapping heat in. As the levels of greenhouse gases in the atmosphere increase so does the earth’s temperature as more heat is trapped. Part of our carbon dioxide emissions are also absorbed by our oceans which affects the acidity of the water. The more carbon dioxide in water the more acidic which has a detrimental effect on marine life.
The increase in temperature, caused by carbon emissions, also has a large number of knock-on effects such as sea levels rising, extreme weather, droughts, and the extinction of wildlife.
How is Carbon Emitted?
Carbon is primarily emitted in buildings by the burning of fossil fuels, the release of refrigerants, and the disposal of waste.
Whole Life Cycle Carbon Emissions
Whole life cycle carbon emissions refer to the carbon emissions from the production of materials and products, the construction process, and the end of life. Only operational carbon emissions are currently considered to count towards carbon zero status, all other carbon emissions are considered embodied carbon which is significantly harder to measure. Embodied carbon and whole life cycle carbon emissions will be covered in detail in a later article.
Figure 1: Whole Life Carbon Emissions For a Building
Energy Efficiency vs Carbon Emissions
Energy efficiency refers to using less energy to produce the same outcome such as heating, cooling or lighting a building. This has typically been the focus as lower energy consumption results in cost savings. Reducing carbon emissions is related to energy efficiency however, the type of fuel used must also be considered. For example electricity generated by burning fossil fuels has high carbon emissions but generating electricity using solar, hydro-electric or wind has almost zero carbon emissions.
Energy Usage in Commercial Buildings
The overall energy use in commercial buildings is typically broken down as follows:
– Heating, ventilation, and air conditioning (HVAC) ~ typically over 40%
– Lighting ~ Can be as high as 30%
– Water heating ~ Around 7%
– The remainder of the energy use is from office equipment and other miscellaneous uses.
From the above it is clear that making changes to HVAC and lighting will have the most significant impact on carbon emissions.
The Use of Refrigerants in Buildings
Refrigerants are another significant concern when looking at a building becoming carbon zero. Refrigerants are used in some HVAC systems and these refrigerants are released into the atmosphere when a system leaks or if the refrigerant is not disposed of properly. Refrigerants can be thousands of times more damaging than carbon dioxide if released into the atmosphere.
The measurement of how damaging a refrigerant or other greenhouse gas is compared to carbon dioxide over time is called its global warming potential (GWP). Carbon dioxide has a GWP of 1 however, most common HVAC systems use a refrigerant called R410a which has a GWP of 2,088. This means the gas is 2088 times more damaging than carbon dioxide if released into the atmosphere.
The Logistics of Becoming Carbon Zero
1. Design a passive building
Designing a building with passive design principles should always be the first course of action to reduce carbon emissions. Passive design is a practice that utilises natural energy to heat, cool, ventilate, and light a building. Having the sun and wind heat and cool the building greatly reduces the energy required to heat, cool, ventilate, and light a building. We are currently working on an article about passive design for commercial buildings so watch this space.
2. Switch to a carbon zero certified electricity provider
In general, powering your building using 100% renewable energy is straightforward in Aotearoa as the majority of electricity providers generate 100% of their power from renewable sources. Your first step should always be ensuring your energy provider is certified carbon zero.
3. Look at on-site renewable energy sources
While using sustainable off-site energy providers is the best first step you can take, producing energy on-site is a great option for reducing your reliance on the power grid. On-site renewable energy sources might involve installing solar panels, biomass energy, or wind turbines. Any electricity provided back to the grid provides you with negative emissions to offset peaks in power consumption. In other words, your on-site generation does not need to cover your peak loading but it just needs to generate the same amount of electricity that you use in a day. A benefit of solar is that it generates the most energy at peak summer sun times when your cooling load is also the highest.
4. Stop using fossil fuels as an on-site energy source
Gas and other fossil fuels should be avoided completely due to the large amount of carbon emissions they produce. Equipment that uses fossil fuels can be replaced with equipment that uses energy from renewable sources, whether off-site or on-site. For example, instead of using fossil fuels to heat water, heating should be done by equipment like heat pumps, solar heating, wood pellet boilers, and in some instances electric water cylinders. The engineers at RE-SHAPE have reviewed equipment for many clients so get in touch with us today if you would like us to undertake a review.
5. Review the refrigerants you are using
If you are using systems containing refrigerants, the type of refrigerant used should be carefully looked at to ensure it has a low global warming potential (GWP). If the system is operating on a high GWP refrigerant, replacement of the equipment should be considered. RE-SHAPE can quickly assess the refrigerants you are using and give you options for alternatives. Get in touch with us today for assistance.
6. Installing energy efficient equipment
Once you are running on the lowest carbon energy source, focus should be turned to installing the most energy efficient equipment as possible. This might include heat pumps, EC fans, EC pumps, and LED lighting. Get in touch with us today to review your options.
7. Review the design of your HVAC system
Designing your HVAC system to use less energy is essential to reducing carbon emissions. Poor design can have a detrimental effect on energy efficiency and limit equipment life. RE-SHAPE are specialists in HVAC design so get in touch with us today if you would like us to undertake a review of your HVAC system.
8. Review the control of your HVAC system, lighting and other building systems
Controlling your HVAC system, lighting, and other building systems to use less energy is essential to reducing carbon emissions. Proper system control is incredibly important when it comes to saving energy and is often neglected in many buildings. RE-SHAPE are specialists in building control systems. Click here to get in touch.
9. Creating energy management procedures
Creating energy management procedures for building users to follow is important to minimise energy consumption and therefore carbon emissions.
10. Review how you dispose of waste
Waste disposal has an impact on carbon emissions for the building and needs to be considered if you’re going for certification with the New Zealand Green Building Council (NZGBC) or Toitū.
11. Look at carbon emission offset programmes
Once energy is reduced as much as possible, any unavoidable carbon emissions need to be offset through a carbon emissions offset program such as the Toitū Envirocare’s offset programmes.
For more information on the above get in touch and we can undertake a review to reduce your carbon emissions.
Certification
The following certifications allow you to state your carbon zero status with confidence and against industry benchmarks. The differences between the certifications are stated below.
NZGBC – carboNZero Building Operations
The NZGBC – carboNZero Building Operations certification will certify your building.
Toitū – Carbon reduce or Carbon Zero
Toitū certifies businesses as carbon zero and focuses less on the building and more on the operational choices.
Conclusion
Whether your goal is to meet sustainability initiatives, reduce running costs, or do the right thing for the environment, reducing carbon emissions should be factored into any decision-making process. In order to achieve a carbon zero building status each of the steps detailed above need to be addressed. These include reviewing your energy sources, energy usage, refrigerants, waste disposal and carbon offset programmes.
For more information on the above get in touch and we can undertake a review to reduce your carbon emissions.
Further Reading
If you’re also interesting in learning more about going carbon zero check out our article below.
