The construction sector is revolutionising the way that we live, developing more sustainable materials and more environmentally friendly ways to build and insulate our homes. However, it still accounts for nearly 40% of the world’s carbon dioxide emissions, much of which is created by manufacturing building materials, such as steel, glass and cement.
With the construction sector set to double by 2060, at present only around 3% of new construction is considered ‘green’. We see sustainable construction as essential for the future of our planet and subscribe to the Living Building Challenge ethos that every act or decision in construction has the power to make the world better for all. At Clear Architects we are leading, and pushing our industry to make the changes.
What is Net Zero?
Simply put Net Zero is the achievement of reducing greenhouse gas emissions to be as close to net zero carbon, as possible, with the re-absorption of any remaining emissions from the atmosphere. It is a key weapon in battling climate change. The UK Government has set the target of achieving Net Zero emissions by 2050.
Net Zero and the Built Environment
Reducing Carbon Emissions and Embodied Carbon overall from the Built Environment involves examining the whole life cycle of our buildings. From their inception through construction, daily use and beyond.
What causes Carbon Emissions?
The primary sources are the burning of fossil fuels for electricity and heat, agriculture, transportation, deforestation and manufacturing. High levels of emissions contribute to Climate Change.
The accumulation of carbon emissions going into the Earth’s atmosphere causes long-term warming of the planet’s temperature. This has been speeded up during the last century by the burning of fossil fuels, the increase in the world’s population, extensive farming, deforestation and rapid developments in manufacturing.
The loss of bio-diverse habitats and increased pollution has also contributed to a weakening of the planet’s ability to absorb emitted carbon, creating an increasingly catastrophic cycle. it is why our schemes are designed holistically to achieve Bio Diversity Net Gain – way ahead of the Environment Bill due later this year.
The long-term effect of a warming planet impacts the melting of the Arctic ice caps, rising sea levels and flooding. In other areas, it creates intense heat waves and drought.
What is Embodied Carbon?
This means all CO2 emitted by the extraction, manufacture, transport and installation of materials. In construction, this spans from the extraction of raw materials to their construction on site.
What is Net Zero Architecture?
Net zero buildings
To reduce carbon emissions to a net zero carbon building (or carbon neutral), architects must look at the original site characteristics, the design process, material choices and construction philosophy to build sustainable buildings of the future.
Net Zero architecture cancels out the greenhouse emissions produced during construction by reducing buildings’ carbon footprints, implementing ways to absorb carbon dioxide from the atmosphere, and increase bio-diversity.
Reduced energy use by improving building performance is also key for the Net Zero experience.
According to LETI around 18% of the UK’s annual emissions come from existing homes, and the Green Building Council estimates that 80% of these homes will still be in use in 2050. This means that decarbonising existing buildings will play a critical role in our advancement to a Net Zero world.
Constructing new Net Zero buildings will also play a critical role in helping battle climate change.
Reducing embodied carbon
It is estimated that around 20% of global emissions are caused by concrete, steel and aluminium. Through careful design and thoughtful material selection, it is possible to reduce the embodied carbon impact of the buildings we create. Choosing materials with recyclable content or from renewable sources such as reclaimed bricks and steel, recycled aggregates and plant-based insulation means we can create buildings without compromising on quality.
To create the most sustainable designs, it is vital to consider the environmental impact of a building across its whole life cycle, not just during the construction stage. By choosing durable, high-quality materials we can reduce the long-term maintenance, repair and replacement costs.
The amount and type of energy used in buildings is another key consideration for net zero energy buildings.
With energy becoming increasingly expensive the more a building uses the more costly it is to run. According to the ONS the average electric bill rose by over 66% between 2022 and 2023 and the average gas bill by over 129%. As the demand for more energy grows, pressure on prices will continue to build.
The high carbon emissions that come from the burning of fossil fuels is not viable any more.
Designing highly efficient buildings that use renewable forms of energy helps address climate change and address the climate emergency we face for our planet.
What is Renewable Energy?
This is energy that comes from sources such as sunlight and wind which are constantly and naturally replenished. This is in direct contrast to fossil fuel use like coal and gas which have a finite source.
Naturally replenishing energy sources are the answer to gaining a consistent energy supply that is abundant and kinder to our planet.
When looking at the construction of buildings it is important, from a sustainability point of view, to look at the operational energy required during the life of a building. This includes the lighting, heating, cooling, and ventilating systems plus the operation of appliances.
Building Regulation Targets
The building regulation targets for domestic premises are set at a reduction of 75% of operational energy by 2030. As a chartered RIBA (Royal Institute of British Architects) practice we use the Mesh Energy Hierarchy seen below on our projects, to focus on how energy can be reduced through clever design at every stage of a building’s construction and operation.
What is Passive House Design?
Passive house design is a high bar of sustainable architecture, providing thermal comfort and greater energy efficiency to create a comfortable home environment. It can be very expensive, so if budgets are tight we use the ‘principles’ of those set by the Passive House Institute in our designs.
There are 5 key principles to passive House design:
- Airtightness – to achieve maximum energy efficiency, buildings need to be constructed with extremely low air leakage.
- Thermal Insulation – to provide thermal separation between heated/cooled indoor spaces and the outdoor environment by using thick and continuous insulation.
- Mechanical Ventilation Heat Recovery – (MVHR) is the process of improving the fresh air quality within a building without opening windows or doors.
- High-Performance Windows – these need to be airtight and ideally double or triple-glazed. An important element of green building design is utilising solar gain to warm spaces in winter whilst reducing overheating during the summer months.
- Thermal Bridge Free Construction – this means ensuring that insulation is continuous with limited paths through it to allow heat to travel.
What is Bioclimatic Design?
Bioclimate design looks at the local climate and environmental resources to design buildings with natural thermal comfort.
How Do We Achieve Net Zero Buildings
COP 21 finally made the World sit up and listen a bit more closely to what climate change actually means. The construction industry is a big part of the problem, accounting for around 38% of energy-related emissions.
Using Renewable Energy systems
The Net Zero design process begins with looking at what sources of renewable energy can be used to the best effect. Orientation of a site is crucial to harnessing the energy of the sun and photovoltaic panels (solar panels) are an important element in any Net Zero design.
Energy Efficient Design
It is important to keep operational carbon emissions to a minimum during the lifecycle of a building. As Net Zero architects, we look first and foremost at the efficiency of our designs and the natural context of their location. We ensure that the building is well insulated thermally which regulates the heating and cooling of spaces to avoid excessive energy consumption. As well as the energy savings this also makes for comfortable spaces without wildly varying temperatures.
Alternative heat sources
Heat pumps are an incredible way of heating a building efficiently from renewable energy. The two main types are Air and Ground which use the heat in the air or ground respectively to heat water in the heating system to a certain level which is then further boosted to heat buildings via radiators or underfloor heating, and hot water for general use. Air Source Heat Pumps in particular are set to become a popular choice for new homes as Gas Boilers cease production from 2025. A target set in alignment with the World Green Building Council.
Avoiding building methods that require significant concrete foundations and brick/cement construction is one of the main ways to reduce carbon emissions, as concrete for example releases a high level of carbon during manufacturing. That said, there are recycled concrete options now. Wood is a renewable source that absorbs carbon while it grows, so it reduces the carbon impact within a building. Glass is somewhat a double-edged sword as it releases a lot of carbon during manufacturing however it is recyclable and the use of high-quality glazing orientated correctly, produces a lot of useful solar gain which feeds back into the thermal efficiency of the building by utilising ‘free’ self sufficient energy from the sun.
Pre-fabricated and off-site construction
Achieving high-quality end buildings and reducing waste in the construction industry are key factors to consider in the pursuit of good environmental design and sustainability. Manufacturing large parts of a building off-site addresses both in sustainable living.
SIPs/ Closed timber panels/ ICF Construction
We are a big advocate for using modern methods of construction that employ off-site procurement routes. On top of their sustainable design credentials as solutions for new buildings. They also generally require much shallower foundations than their more traditional masonry counterparts, which equals less concrete in the ground and reduces time on site.
For instance, the average house could take only 2 weeks to install the structural shell if built using SIPs, in comparison to a brick and block house which might take 12 weeks.
Is there a Net Zero certification?
There is no one standard which provides certification, but there are various companies which will measure emissions and offer proof of a Net Zero energy building.
What does a Sustainable Future for the Construction Industry look like?
Our successful planning application for St Lawrence Farm within the Hertfordshire Green Belt is a bold example of how Net Zero Energy architecture can be achieved. This unique development for an extended family consists of 4 individual properties each achieving passive house principle standards.
The site orientation, existing building fabric, topography and limitations of a Green Belt site were all extensively explored and heavily influenced the proposals.
Renew or Rebuild?
This is often our starting question when approached by a client, do we improve or do adaptive reuse or start again? There is no definitive answer to this and it is mostly determined by the existing building’s unique circumstances and there are many different reasons for choosing either path.
Renewing/ retrofitting an existing building helps the owners/occupiers lead more comfortable, affordable and sustainable lives whilst helping global climate action targets. However, to create a home that meets net zero energy standards in its own right, new buildings are typically the answer.
Consider the Site Context
With St Lawrence Farm, the existing site had a number of unattractive and inefficient buildings perched at the top of an elevated slope, with the wrong orientation for passive energy use or design. Our client wanted to change this to create a uniquely more sustainable living scheme for their family, that would nestle less obtrusively into the landscape.
Operational Net Zero energy buildings
We decided to replace the current buildings with 4 exceptionally sustainable dwellings with a shared pavilion building for the individual families to spend time together in. Each house is individually designed with openings located to maximise solar gains yet limit heat loss and a fabric first approach. The use of renewable technologies harnesses natural energy from the sun and earth, allowing them to achieve operational Net Zero, maximising energy savings.
To generate heat for the houses, a horizontal ground source heat pump provides space heating, and domestic hot water. Electricity is generated via roof-mounted solar panels and a ground-mounted solar array utilising an existing south-facing slope in the landscape. The development as a whole is designed with on-site renewable energy sources and is as off-grid as possible allowing it to be self-sufficient and reduce loads on the energy grids.
To ensure that the drainage systems are as sustainable as possible, the design includes rainwater harvesting, a sewage treatment plant, and water ponds formed to overflow with clean water to the existing brook on the western boundary.
Each house is constructed using a proprietary Insulated Concrete Formwork (ICF) system. This construction method has many sustainable and efficient benefits to achieve a Net-Zero building. It results in a quicker construction time due to offsite manufacturing and on-site assembly, reducing waste and dust pollution. The lightweight formwork can be delivered in smaller, greener vehicles rather than lorries, further reducing the project’s embodied carbon footprint.
Making Net Zero the Norm.
It has never been so easy to make good sustainable choices and the construction industry is making leaps and bounds in technology, building science and material development. But making the necessary changes is slow to develop throughout an industry which is focused on ‘cost and speed’ rather than the environment, we are aiming to change that to ‘quality and planet’.
The UK Government’s mandates on insulation and greener energy will make a difference in the long run but construction companies need to work with architects like ourselves and get on board to make the industry part of the solution rather than the problem.
As the Living Building challenge asks “What if every single act of design and construction made the world a better place?”. Now isn’t that a great aim to aspire to!
Clear Architects is an ambitious and established architectural practice with studios in Epping Forest and the New Forest.
We are a RIBA Chartered practice and RTPI Chartered practice, renowned for “exceptional and sustainable” architectural design with an impressive success rate on planning proposals within the Green Belt and areas of outstanding natural beauty. Chat to us about building your dream home.