As the demand of a sustainable lifestyle increases, cities are trying to find strategies to create environmentally friendly communities. From passive designs to recycled materials, architects are turning their attention to climate change and trying to find solutions through architecture and design.
Every building in the world — every home, office, school, factory — needs to be net zero carbon by 2050 to keep global temperatures below 2 degrees C. Estimates suggest that exceeding 2C by 2030 at least $4 trillion in assetswill be at risk and another 100 million people driven into poverty.
Cities account for more than 70 percent of global carbon dioxide (CO2) emissions. About half of those emissions come from the energy consumed in buildings for lighting, electricity, heating and cooling. Moreover, cities in emerging economies will account for the majority of global growth in energy use through 2030.
This is far more challenging than greening electricity generation or even transportation. Few of the world’s estimated 1.7 billion buildings are net zero carbon today. To change this a multi-partner global initiative called Zero Carbon Buildings for All, was launched at the 2019 UN Climate Action Summit in September 2019. Participating countries including Kenya, Turkey, the United Arab Emirates, and the United Kingdom have committed to national and local policies to make all new buildings net zero carbon by 2030, and existing buildings by 2050.
Last year the World Green Building Council (WorldGBC) launched a similar effort called Net Zero Carbon Buildings Commitment for businesses, property developers, cities and regions with the same targets.
What is a net-zero carbon building (ZCB)?
Net zero carbon buildings, as defined by the World Green Building Council, are “buildings that are highly energy efficient and fully powered from on-site and/or off-site renewable energy sources.” Thus, for these buildings, the energy consumption is offset by renewable energy produced. Many countries and cities have expressly set goals for net zero buildings in an effort to meet the highest standards set by the Paris Agreement.
Research shows that reducing energy demand in buildings represents the most cost-effective way to tackle climate change. ZCBs can also have important co-benefits, like improving health and quality of life for residents and workers.
The route to Zero Carbon
There are clear imperatives to reduce the carbon emissions resulting from the built environment. However, we are currently not achieving any significant year-on-year reductions and, unless new policies embodying new standards, incentives and penalties are put in place, we are unlikely to do so.
Setting a Zero Carbon target for our new housing would be a clear and bold step to achieve genuine emissions reductions and many cities and regions are moving towards this goal.
However, understanding what this actually means and how to achieve it is far from clear.
Examining data from Energy Performance Certificates (EPCs) as well as monitored data from real buildings, shows us that, there are three problems with adopting a net zero emissions approach:
- There is a performance gap between predicted heating energy demand and actual energy use
- There is a seasonal disparity between energy demand (heating in winter) and renewable energy generation (solar PV in summer alongside wind in the autumn and winter). This indicates a need for inter-seasonal energy storage which will result in storage losses
- There are limits to how much renewable energy can be deployed and managed through the national grid
As a result of these problems, a notionally zero carbon home, would not have zero CO2 emissions, but would still emit 18 Kg CO2/m2 year, and an average 68m2 new home in the UK would need 28 solar panels to actually achieve zero net operational carbon emissions, far greater than the amount of roof space it has available.
Extrapolating this to a national level shows that this model of zero carbon is not achievable as the increased grid capacity, storage capacity as well as the space and cost of the renewable generation required to support this is simply not achievable.
In contrast, an equivalent Passivhaus would need only 14 solar panels, dramatically reducing the requirement for grid and storage enhancements and halving the amount of renewable generation capacity required. Reducing the heating energy demand through a fabric first approach is therefore the only practical way to achieve zero carbon homes in reality.
If the zero carbon ‘boundary’ is expanded beyond the individual building to the national level, then achieving a net zero operational carbon built environment is possible if the fabric efficiency levels of our new homes are increased to Passivhaus levels.
The framework
The net zero carbon buildings framework sets out definitions and principles around two approaches to net zero carbon, which are of equal importance:
A/ Net zero carbon — construction
When the amount of carbon emissions associated with a building’s product and construction stages up to practical completion is zero or negative, through the use of offsets or the net export of on-site renewable energy.
B/ Net zero carbon — operational energy
When the amount of carbon emissions associated with the building’s operational energy on an annual basis is zero or negative. A net zero carbon building is highly energy efficient and powered from on-site and/or off-site renewable energy sources, with any remaining carbon balance offset.
Developers aiming for net zero carbon in construction should design the building to enable net zero carbon for operational energy, and where possible this should be achieved annually in-use. Net zero carbon for both construction and operational energy represents the greatest level of commitment to the framework.
C/ Net zero carbon — whole life is also proposed at a high level, but further work will be needed to define the scope and requirements for this approach.
When the amount of carbon emissions associated with a building’s embodied and operational impacts over the life of the building, including its disposal, are zero or negative.
Top 10 essential benefits of NetZero Buildings
- Affordable construction with zero running costs — ultra-low lifecycle costs
- Airtight construction
- Clean energy generation and revenue from integrated solar PV roofs
- Multi-award-winning design
- Meets the ESFA design and layout specification
- Negative carbon emissions asset rating
- Excellent levels of insulation minimising heat loss
- Rapid construction — we spend very little time on your school site
- State-of-the-art energy efficient heating and cooling can cost you very less
- Zero running costs for energy. Significantly reduced maintenance costs
Blog courtesy - Medium.com
