The building sector is responsible for 40% of primary energy consumption and up to 50% of overall carbon emissions. Do you know where these emissions originate from? Are you clear on how the built environment can be designed and operated in order to drastically lower greenhouse gas emissions? Can you talk to the business case for doing so?
This article you will increase your understanding of energy efficiency, and learn how your work in the built environment can help reduce the carbon emissions responsible for the global greenhouse effect.
How does the built environment contribute to greenhouse gas emissions?
Energy use and carbon emissions are strictly correlated, as energy production in our economic system relies mostly on fossil fuels combustion. Although renewable energy (solar, wind, hydropower etc.) is on the rise, we can assume for now that the largest portion of energy use is carbon intensive.
In broad terms, carbon emissions in the built environment are associated with:
Operational carbon in buildings and infrastructure: space heating, lighting, outdoor lighting, waste from construction, demolition, water supply, wastewater treatment and disposal, etc.
Embodied carbon from the manufacture and production of materials and products, construction processes, transport and in general all emissions involved in the lifecycle of products and services.
As professionals in the built environment industry, you most likely have influence to some extent on one of more of the issues above. But how? We will now look at practical ways to reduce carbon.
How can we reduce carbon emissions?
As climate change is one of the biggest environmental challenges, naturally reducing carbon emissions is one of the highest priorities in sustainable design.
A number of regulations and policies (from national to local) for the built environment aim to bring standard practice in line with the international carbon reduction targets.
Your first priority is therefore work in compliance with these. However, to revert the current upward trend of carbon emissions, you are asked to work above and beyond compliance.
Strategies related to energy consumption in buildings can be explained in three hierarchical steps, that are can be displayed as the Energy Pyramid.
Energy conservation: these strategies are often the least expensive and they aim to reduce energy demand of buildings as a first set of actions.
Energy efficiency: this is about meeting the demand for energy with high efficiency technology and mechanical systems; it is about getting the most out of the energy inputs.
Renewable energy: including more and more renewable energy into the equation relieves the pressure of fossil fuel based energy production.
Lets look at each of these sections with practical strategies, bearing in mind that the approach to energy efficiency always needs to be considered holistically, and you will notice that most of the following design actions are interconnected with each other.
How can we reduce the overall energy demand?
The main idea is maintaining a balanced temperature indoors by adapting the building to the external climate conditions, gain extra energy from the sun and maintaining cool in summer.
Occupant behaviour and facility management: occupants are made aware of their energy consumption habits through metering, raised awareness feedback systems, zoning of heating and cooling units.
Building envelope/fabric: well insulated and airtight buildings retain more energy. Please remember of provide appropriate internal ventilation strategies (both natural and mechanical) especially in buildings with high airtightness.
Passive design strategies: Using passive design measures suitable for the climate and the site during all seasons. Some examples are building orientation to give appropriate solar gain (e.g. glazed surfaces), maximising the use of daylight and enhancing natural ventilation.
Consider overheating: during summer there could be considerable energy loads for air conditioning in buildings; consider passive strategies for overheating such as shading systems or night time cooling through natural ventilation.
Low embodied carbon materials and products: choosing low embodied carbon materials in construction and interior design indirectly helps lowering emissions.
Smart construction strategies: emissions during construction could be significantly lower when smart strategies are adopted to source energy and materials. Offsite construction also offers advantages as an optimised system of construction.
Design to lower transport emissions: Infrastructure design that encourages walking and cycling, e.g. safe pedestrian and cycle routes.
How can we enhance Energy Efficiency?
Energy efficiency strategies aim to meet energy demand with technology designed to have the most optimised energy outputs, and therefore needing less energy for the performance levels required. Some examples of effective energy efficiency strategies are:
Heating/Cooling systems: choosing suitable / appropriately sized heating and cooling equipment for the building function and the most efficient possible. The most appropriate technologies need to be estimated case by case (e.g. link to district heating, cogeneration etc)
Lighting: Using low energy lighting such as LEDs, which can reduce energy consumption and are more durable than traditional lighting systems. Efficient external lighting and security lighting should also be considered.
Appliances: Choosing highly efficient appliances and white goods. The energy performance of appliances is described in an official energy label (the EU Energy Labelling Scheme[3]) and can be a significant part of the electricity consumption of a building.
Controls: Using motion sensors, smart metering and zonal controls to react intelligently to building user needs. These are especially useful for areas with less frequent use like toilets or circulation.
.. and increasing Renewable energy?
Renewable energy generation means that its source is not finite like fossil fuels but virtually endless natural sources. These systems are increasingly becoming cheaper, more efficient and better integrated in the built environment. Some examples of renewable energy systems are:
Photovoltaic panels, which convert sunlight into electricity and can utilise often unused urban roof space.
Solar thermal, roof mounted panels could typically provide up to 80% of hot water requirements.
Wind turbines, currently provide around 11% of the UK’s power, but beware of their use in the urban environment, where there is low wind speed
Biomass boilers: burning of wood/organic matter
Hydroelectric and tidal power plants: these harness the power of water movement.
Don’t forget, most successful energy strategies include…
If you wish to take action that is appropriate and durable, we recommend including the following steps in the energy strategy for your projects:
Assessment: it is very useful to establish what the potential energy demand is for a new building, it gives you an understanding of the most important areas for improvement in the design. For existing buildings, assessments are very useful to identify where there currently is higher energy loss and therefore designing for remediation.
Post Occupancy Evaluation (POE): it is understood that often assessments and projections of the energy consumed could be misleading. This is what has been defined as the performance gap; for this reason, it is very useful to monitor the energy performance of buildings and ensure that there is a feedback loop which informs maintenance and future design.
How can businesses benefit from lowering carbon emissions?
Demonstrate that your business is future-proof and cutting-edge
Capture new business opportunities making your business more competitive and drive innovation
Demonstrate your business’ leadership in advancing the sustainability agenda
There are substantial risks for business for not actively pursuing the sustainability path:
There are risks of losing business and reputation for organisations, when they fail to demonstrate their alignment with commitments to keep global warming below 2ºC
Properties with carbon intensive technologies may be at risk from asset stranding
Many companies may be hit by future costs from carbon regulations
Does your business go beyond compliance, does it take creative approaches in finding smart, cost-effective solutions for the design and operation of buildings and infrastructure?
Remember that a wide range of innovative design and operational strategies are available to you, and together with your creative input there are infinite possibilities and opportunities for continued improvement across the industry!