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Three ways architects can reduce the carbon footprint of their designs

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Why does the carbon footprint of my design matter?

The UN Environmental and the International Energy Agency has estimated that the built environment makes up around 40% of all energy-related carbon emissions. The construction industry is, therefore, a carbon-intensive sector in the UK economy.

Being carbon-intensive is an insecure status. With increasing pressures from the British government and international agreements for a Net-Zero 2050, high carbon industries will likely be subject to strict regulations. Additionally, with the UK aiming for a 68% reduction in greenhouse gas emissions by 2030, these pressures will be ‘front loaded’ over the next ten years.

Low-carbon is also increasingly popular with consumers. Increasing environmental consciousness and financial incentives for the adoption of ‘clean’ energy will likely make low-carbon credentials a selling point. Moreover, property shoppers are increasingly wary of offsetting methods as a carbon reduction solution. Some see it as ‘buying’ out of climate accountability (Anderson and Bernauer 2016). Therefore, considering long-term sustainability methods when designing your next building will likely make it a more attractive property investment (BREEAM 2021).

In short, to ensure the long-term success of your next building design, it will be essential to factor its carbon footprint into your planning.

The architecture industry is preparing for a low-carbon future

The architecture industry is prioritising sustainability more and more.

In 2019, The Royal Institute of British Architects (RIBA) declared a climate emergency and confirmed their support for Net-Zero 2050.

RIBA has since launched its ‘2030 climate challenge’ to encourage forward-thinking architects (particularly RIBA chartered practices) to consider environmental sustainability in their designs. The challenge lays out a series of targets for reducing the sector’s carbon footprint to reach the 2030 and 2050 goals set by the UK government. You can get in touch with the RIBA to receive an assessment on your practices sustainability performance here.

This article will outline examples of low carbon considerations to factor into your next design. It will include both embodied and operational carbon. The former is the carbon emitted in the materials production, transportation and construction of a building. The latter, the carbon emitted whilst the building is occupied.

It will include innovative examples of eco-homes and analysis of tangible standards that will govern the sustainability rating of your building, such as those from BREEAM.

Carbon footprint reduction: Location and transport options

An architect will no doubt focus on the experience of the eventual occupant. However, it’s essential to consider how the design of your new build may facilitate the sustainability of their lifestyle.

Operational carbon from buildings makes up 28% of the global energy-related carbon emissions (World GBC 2021). This generally relates to factors like its thermal efficiency or energy source type. However, a less considered factor is the ease of sustainable lifestyles, such as transportation to the location.

In his 2014 Ted x talk, LEED (an environmental rating) accredited architect Bryn Davidson gives an example. He describes a revolutionary eco-home with solar panels, a high standard of insulation and a timber frame.

However, it also has a huge car park. This is because the eco-home is only accessible by car. Despite all the best technologies used and money spent to achieve a sustainable design, the occupants will have a higher carbon footprint due to their transport needs. The architect considered the innovative solutions but not the basic lifestyle of those who would live there.

Transportation availability is a key part of the most recent BREEAM specifications for environmentally responsible construction. It specifies easy access to more sustainable means of (public) transport that will reduce the CO2 emissions over the life of the building (BREEAM 2018).

Carbon footprint reduction: Thermal efficiency

Heating contributes to around 30% of the UK’s total greenhouse gas emissions (EDF 2021). Therefore, reducing energy wastage in domestic homes has been identified as one of the ‘primary’ methods for reducing greenhouse gas emissions by the UK government (BEIS 2017).

Moreover, in 2021, 77% of homes still use carbon-intensive gas for their central heating. If heating a home produces carbon, an obvious way to reduce its carbon footprint is reducing the amount of heating needed. That’s the goal of thermal efficiency methods.

Domestic energy efficiency is also the largest subsector in the low-carbon and renewables economy, making solutions more accessible and affordable (BEIS 2017).

These considerations can be as simple as introducing double glazing and efficient wall insulation. However, there are also more far-reaching solutions for increasing the thermal efficiency of your design.

The Passivhaus standard

Passivhaus is a high set of standards for airtight thermal efficiency. They take very little energy for heating and cooling, meaning a significantly reduced operational carbon footprint and cheaper energy costs for the occupants.

The Passivhaus standard is named because it is heated chiefly through passive sources such as the sun or people who live there. You can use the Passivhaus Planning Package tool to consider this level of airtight heat efficiency in your next design.

In 2019 the North East saw its first-ever Passivhaus overlooking the river Derwent in Tyneside (Tracing Green 2019). Built by the sustainable architecture firm MawsonKerr the house was ‘upside down’ (bedrooms at the bottom) to give it panoramic views of the river.

However, most significantly, its airtight design means the carbon footprint caused by heating and cooling the house is almost nothing.

Low carbon insulation

Insulation is a central part of the Passivhaus method and many other paths towards reducing the operational carbon emissions of a design. The UK’s sixth carbon budget also notes insulation as crucial for achieving a Net-Zero construction sector by 2050.

Insulation and airtight design can significantly reduce your building’s operational carbon footprint. But what if you could similarly reduce the embodied carbon of your chosen insulation material?

There is a significant amount of innovation in this field. However, one exciting new developing product is Thermulon aerogel insulation. Initially used by NASA to insulate space ships, a 10mm layer of aerogel can reduce heating demand by 25% compared to standard materials (Guinoa et al., 2017).

The embodied carbon of this material is very low as it can be made from industrial waste.

Heat pumps

Described in the fourth UK Carbon budget as a ‘key option for supply-side decarbonisation’ (CCC 2010), heat pumps are another, more easily accessible method for increased thermal efficiency.

A heat pump transfers heat from a source to another location. For example, the warmth from the garden soil to the radiators in your house. They use a small amount of electricity to move heat from a cooler space into a warmer one, the opposite of how it moves naturally. In short, it’s like a reverse fridge.

Despite using a small amount of energy, installing a heat pump instead of a gas boiler can save you 23 tonnes of CO2 over ten years, the same amount as thirty flights to and from Madrid (EDF 2021)!

Moreover, the UK government has banned new gas boilers from 2025. Therefore, finding low carbon alternatives is now a priority for architects.

Airtight design, innovative insulation materials and sustainable heating methods can improve the thermal efficiency of your building. This means it will take less energy to heat and cool it and, in turn, will reduce the carbon footprint of the building.

Carbon footprint reduction: Using low carbon materials

These options for increasing thermal efficiency are mostly related to operational carbon output (the carbon emissions caused during the building’s occupation). However, 11% of the energy-related carbon emissions in the UK come from embodied carbon (the production, transportation and construction of the building and its materials).

Choosing low-carbon materials can significantly reduce the embodied footprint of your design. With the British government investing more into green technologies for the construction sector each year, there are a growing number of low-carbon materials to choose from.

Choosing low-carbon materials can significantly reduce the embodied footprint of your design.

Concrete alternative: spheraLite and spheraZero

Concrete and cement contribute 5 – 10% of global greenhouse gas emissions (Geopolymer Tech 2021). Therefore, using concrete in your building will significantly increase the embodied carbon emissions of your design.

However, concrete is still a valuable and widely used material that could be necessary for your build. That’s why innovative new technologies are working to decrease its carbon footprint.

Sphera has invented the word’s first carbon negative (spheraLite) and carbon-neutral (spheraZero) aggregate concrete blocks. This means that rather than adding to your design’s carbon footprint, Sphera blocks either have no impact or actively reduce your impact compared to using incumbent materials. If you want to reach Net-Zero design, spheraLite can also help you mitigate hard to reduce emissions elsewhere in your project.

If you were building ten typical three-bed houses, you could save 72 tonnes of CO2 using spheraLite and spheraZero. That’s the same as planting 1200 trees.

Using Sphera’s blocks can replace a carbon-intensive material in your design with one that is carbon neutral or even carbon negative.

You can check out Ryder architecture’s article on Sphera, part of their Net-Zero series, to learn more.

Structural alternatives such as timber

Another carbon-intensive building material is steel. Similarly to concrete, it has a large carbon footprint, making up 5% of global greenhouse gas emissions. One tonne of steel can emit up to two tonnes of CO2eq.

In short, steel is a common, high-carbon material that will negatively affect the environmental rating of your design.

An accessible structural alternative is timber. This type of biomass sequesters (removes) carbon from the atmosphere whilst the tree is growing.

Using materials such as cross-laminated timber is an excellent alternative if you are looking for a structural material with lower embodied carbon. It’s also more easily recycled than other timber, so it has a higher end of life value.

You can also check out our list of low carbon materials.

In short

Whether it’s transportation links, operational carbon emissions from energy waste or the embodied footprint of your materials, the carbon footprint of your new design has never been more crucial.

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