The term ‘carbon footprint’ refers to the total greenhouse gas emissions associated with a particular policy, individual, event, development or product. he term ‘carbon footprint’ is similar in meaning to ‘embodied energy’ which refers to the total energy consumed by a building or product throughout its life, including; initial embodied energy, recurring embodied energy, operational energy and demolition energy.
According to Architecture2030.org the built environment generates nearly 50% of annual global co2 emissions, of these total emissions, building operations are responsible for 27% annually while building materials and construction are for 205. Achieving 0 emissions from existing buildings will require leveraging building intervention points to accelerate the rate of energy upgrade. Achieving the same for new buildings will require energy efficiency using no on site fossil fuel; and renewable energy sources.

The UK construction industry is the largest consumer of resources, consuming more than 400 million tonnes of material a year (ref. Davis Langdon), and this consumption of materials in itself accounts for around 10% of UK carbon emissions
In the current climate crisis, the building industry addresses a relatively new but equally important element while considering the ever expanding climate change that is  carbon footprint. Since the beginning of construction buildings and facades had three prime functions - 
•    Shelter from the outside elements
•    Providing daylight 
•    Aesthetics 

A building’s façade is the first impression of a building; it can be a key feature with multiple functions. Embodied energy in buildings was first considered when the industry began to undertake detailed life cycle assessments, evaluating the whole-life environmental load of buildings. It had been assumed that service and maintenance operations during a buildings life consumed considerably more energy than the processes used to construct it.

Consequently, a building’s facade can often be replaced before the end of its designed shelf life, resulting in an increased amount of whole – life carbon emissions.The choices opted by the occupants or the builder and designer during this replacement cycle can play an important role in minimizing or maximizing embodied carbon. Façade design decisions must consider the embodied carbon impacts associated with the production, installation and as well as operations.
The full, life-cycle ‘cradle-to-grave’ embodied energy a building therefore is the initial embodied energy plus the recurring embodied energy plus the demolition energy. Cradle-to-grave is: ‘A boundary condition associated with embodied carbon, carbon footprint and LCA (Life Cycle Assessment) studies. It includes the cradle to site results but also includes the GHG (Greenhouse) emissions associated with the in use of the material or product (maintenance) and the end of life (disposal, reuse, recycling).’

Carbon footprints are very difficult to calculate accurately because of the complexity of the life cycle of the elements being analysed, which can include multiple components, comprising many raw materials, which have to be extracted, processed, transported, manufactured, operated, disposed of and so on. As a result, a number of carbon footprint calculators have been developed to help produce consistent, and so comparable, results.

HOW TO CALCULATE BUILDINGS IMPACT ON THE ENVIRONMENT? 

 

• Pick a measurement method – you might consider the GREENHOUSE GAS PROTOCOL from WORLD RESOURCES INSTITUTE or use a simple way by creating a ballpark assessment of emissions.

           The bulk of a buildings footprint is energy use including electricity, natural gas etc.

           Some basic calculation and utility bills can reveal a large portion of this impact.

• Select an emission scope – the GREENHOUSE GAS PROTOCOL clarifies emissions into 3 scopes

            SCOPE 1 – highest degree of control such as burning coal or gas on site.
            SCOPE 2 – encompasses grid electricity or offsite heating and cooling sources including purchased electricity, steam or chilled water.
            SCOPE 3 – accounts for emissions with the least control or ownership such as employee travel and commuting, etc.

•  Calculate using number of online and offline solutions. 

            The awareness of the problem of fossil fuel consumption in the built environment emerged gradually in the years.

One of the most common carbon intensive materials used in façade is aluminum, it has an energy intensive process and is responsible for around 1 % of global     greenhouse gas emissions. By 2050 the estimated global usage of aluminum is expected to be tripled, this rise in demand and supply will be needed to be met through   carbon intensive virgin aluminium such as bauxite.

The bauxite supply chain as demonstrated by building.co.uk explains the whole process and the distance covered from the extraction to the fabrication process before the final product is delivered. This demonstration gives us an idea that careful selection of an aluminum supplier is a dominant choice and decision that can help to reduce or increase the embodied carbon of the final product. China which is the world’s largest producer has a coal dominant smelting plant whereas Latin America has a renewable smelting plant, choosing the renewable option can provide a green signal to the other producers to invest in low carbon technology. One of the simplest ways to reduce aluminium embodied carbon is to use aluminium with higher RC (RECYCLED CONTENT), also sourcing aluminium produced using renewable hydro energy instead of old conventional method can reduce carbon by 25%.

Glass and glazing also play an important role in the reduction of the whole life carbon across the built environment. Glass is a significant contributor to embodied carbon of facades ranging from 26% to 60%. Replacing glazing is not a common or convenient system and instead the whole facades are commonly replaced leading to a rise of carbon impact. To make informed decisions assessment of design options according to specific needs of the project is required. Facade design decisions must consider the embodied carbon associated with the production, installation and operational cost of them. 

The need for sustainability in the design, construction, and operation of buildings is a reality. According to the Energy Information Administration, about 40 percent of the energy consumed in the United States in 2015 went directly or indirectly to operating buildings. The good news is there are several steps architects can take to make significant upfront impacts in the design and construction process.

• Reuse buildings instead of constructing new ones. Renovation and reuse projects typically save between 50 and 75 percent of the embodied carbon emissions compared to constructing a new building
• Specify low-carbon concrete mixes Work with your structural engineers to design lower carbon concrete mixes by using fly ash, slag, calcined clays, or even lower-strength concrete where feasible. 
• Limit carbon-intensive materials. For products with high carbon footprints like aluminum, plastics, and foam insulation, thoughtful use is essential
• Choose lower carbon alternatives. 
• Reuse materials. Whenever possible, look to salvage materials like brick, metals, broken concrete, or wood.
• Use high-recycled content materials.