How Green?

The terms ‘green architecture’ and ‘green buildings’ have been very popular during the past few years. Engineering and architectural firms endeavour to prove their environmental credentials by making our buildings more ‘green’. The question is: what are green buildings and how successful are we actually in implementing architecture that is sustainable and environmentally friendly, rather than just ‘green’?

The definition by the US Environmental Protection Agency (EPA) touches on the following themes: Energy Efficiency and Renewable Energy, Water Efficiency, Environmentally Preferable Building Materials and Specifications, Waste Reduction, Toxics Reduction, Indoor Air Quality and finally, Smart Growth and Sustainable Development.  Despite this multitude of parameters, architects and contractors claiming to be green often focus on only one or two characteristics; clearly leaving a lot to be desired. For example, green buildings are often thought of as necessarily energy efficient ones. Although this can be a very important aspect of making a building green, it is definitely not the only one. Despite the fact that this aspect has been highly developed during the past few years, there is still a lot to learn, not only in terms of new buildings, but more importantly, about the energy retrofits of existing buildings.

Even in cases where green buildings actually include all of the aspects described above, there are many factors that contribute to how ‘green’ a building is which are not included in that list. These additional factors are still largely unknown and in need of considerable investigation.  Further, most are left out of the equation when constructing a green building.

The first of these is the lifecycle carbon cost of construction.  This represents the embodied energy and carbon of materials.  This includes the energy for the extraction of raw materials, their processing, their assembly into products and their transport to the construction site.   In some cases, depending on the boundaries of the system, it might even include the energy used for the maintenance of the building over its lifetime, or even for the demolition and disposal of the building at the end of its life. The carbon produced due to this energy is called embodied carbon.

As buildings increasingly become more energy efficient in terms of operational energy use, the importance of embodied energy and carbon grows. The graph below shows operational and embodied energy values for various buildings, mostly focusing on residential case studies. The percentage of embodied energy becomes more significant as buildings consume less energy for their operation. Obviously, in the case of zero carbon building, operational energy is eliminated and it is embodied energy that becomes the main concern.

 

Sartori, I., Hestnes, A. G. (2007). Energy use in the life cycle of conventional and low-energy buildings: a review article. Energy and Buildings, 39 (3), 249-257.

Sartori, I., Hestnes, A. G. (2007). Energy use in the life cycle of conventional and low-energy buildings: a review article. Energy and Buildings, 39 (3), 249-257.

On the other hand, although buildings have become more energy efficient, occupants’ behaviours also change and influence energy consumption accordingly. This might include, among others, the increase of internal temperatures (average internal temperatures in households have risen from 12ºC in 1970 to 17.5°C in 2007) or the augmenting use of gadgets (electricity consumption from domestic appliances has doubled between 1970 and 2002).

Moreover, green buildings should also take into consideration future generations and their requirements. Future-proofing of energy performance in buildings, includes, according to research, not only the lifecycle thinking explained above, but also accommodating for future conditions. This involves climate change, energy availability and, of course, accommodating for risks and uncertainties that affect a building’s energy consumption, including the ‘unknown unknowns’, parameters that at the moment of a building’s design might not even be a topic that is considered.

Furthermore, it is worth mentioning overheating as a major factor to consider when future proofing. As climate change continues, our energy consumption during the summer months will increase because of the increased demand for cooling. Although extreme summer temperatures have not been an issue in the past for the UK, in recent years there has been growing concern about overheating due to its adverse effects, especially on more sensitive populations. At Ecobuild, one of the major UK and European exhibitions focusing on energy and green buildings, a key result was the revelation from the Good Homes Alliance that new-build flats are at high risk of overheating. At the moment there is not adequate evidence to specify the extent to which high indoor temperatures can impose a risk on human health; however overheating in homes has long been linked with health issues. The Health Protection Agency has linked excessive heat to mental health complications, stroke, and heart attacks.

One solution to make sure that the future energy consumption of a building is within its designed parameters is ‘soft landings.’ According to the Building Services Research and Information Association(BSRIA), ‘Soft Landings is the cradle-to-occupation process for the graduated handover of a new or refurbished building, where a period of professional aftercare by the project team is planned for at project inception and carried out for up to three years post-completion.’

The main aspects that define the soft landings process are a commitment to aftercare, using feedback to inform design, focus on operational outcomes, involvement of the end users, setting performance objectives, and communicating and informing all relevant parties of the results. This process facilitates the connection between the design and the operation of a building, which so far has been highly neglected, not allowing designers, engineers and construction professionals to repeat successful techniques or to learn from their mistakes.

To conclude, there is a lot left to be achieved before claiming that we can actually construct the green buildings we design in theory. Encompassing more parameters, but also defining more fully the ones already in use, are very important steps towards really ‘green buildings’ and truly sustainable architecture.

 

Image Credit: Albert Herring via Wikimedia Commons

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