What makes a Building Green?

Green buildings are energy and water-efficient buildings that have a minimal impact on the environment and are conducive for their occupants’ productivity and general health.

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It is hard to tell if a building is ‘green’ based on its appearance. In order to determine if a building is ‘green’ and the degree to which it is ‘green’, there has to be some sort of rating tool that assess different elements of the building. The assessment of these building elements provides an indication of how well the building interacts with the environment, it’s users, and how it utilizes energy resources. There are various green rating tools around the world which are based on the environmental and climatic context in which they are developed. However, these green building standards, practices, and rating tools have a basic common thread that recognise a green building.

What Makes a Building Green?

Reduced Energy Consumption

• Heat gains and losses

In hot climates, such as our own in Botswana, a lot of electricity is expended on cooling buildings through conventional air conditioning. This is because our buildings are not designed to prevent heat gains. Heat gains can be dealt with through alternative building materials, insulation, and air-tightness. Such solutions can keep a lot of heat out of the building thereby reducing the buildings’ cooling loads. Another way of dealing with heat gains and losses is through building orientation. The sun is always low in the east and the west, so having a large area of glazing on these facades leads to buildings overheating as it is harder to shade the sun out at such low levels. North facing glazing allows for some degree of control of heat gains. In the summer, the northern sun is higher and so it can be shaded out through overhangs, etc.

The same principles apply to heat losses. In the cold winter, a lot of electricity is spent on space heating which is also often done through conventional air-conditioning. With poor airtightness, insufficient insulation, and inappropriate orientation, a building lose a lot of heat and this has to be corrected mechanically, with electricity as the energy source. In the winter, the northern sun is lower and can therefore be a useful heat gain for the building. High heat losses in the winter mean greater heating loads. Reducing the amount of space heating required can significantly reduce electric consumption.

• Efficient and appropriate technology

Electric energy consumption can also be reduced by using energy-efficient appliances and lighting sources, as well as through efficient lighting design. It is also important to use the right energy source for the right application. For example, in Botswana, water is typically heated electrically when alternatively it can be heated through solar thermals.

Minimal Environmental Impact

The primary source of heating and cooling energy in Botswana is electricity. The majority of our electricity is generated from coal. Green buildings, while being energy efficient, reduce the amount of carbon emissions associated with the building. A green building has a reduced carbon footprint by virtue of its ability to use less coal-generated electricity. This is not only achieved through its energy efficiency but also by using electricity generated from renewable energy sources with low carbon emissions.

Buildings impact the environment through the amount of waste produced in their construction as well as their operation and the location of the site in relation to the wellbeing of the eco-system. Green building strategies aim to promote buildings that produce less waste and make provision for waste to be recycled. Green building standards also recognize buildings that use recycled content as part of their material specifications.

Conveniently locating the buildings where occupants can access other amenities without the need to drive, or with easy access to public transport, minimizes the amount of hazardous gases released by the vehicles needed to access various buildings. Creating parking provisions that promote car-pooling or call for alternative transport modes, such as bicycles, contributes positively to maintaining clean air.

Increased Occupant Comfort and Productivity

Conventional building design hardly aims to create a healthy and comfortable environment for its occupants. Some buildings have very little to no natural light and external views. These factors have an impact on the occupant’s productivity and energy levels.

Green building standards also require that sufficient fresh air be provided to building users as a way of reducing continuous exposure to stale air. Good indoor air quality is key for minimizing the transmission of infectious diseases.

Some building materials such as paint, sealants, and adhesives contain volatile organic compounds (VOCs). VOCs include a variety of chemicals that can cause shortness of breath, fatigue, and headaches. Using materials that contain less of such chemicals protects the occupants’ health.

Water Consumption

Green building practice recognizes and promotes water-efficient building design. Buildings can achieve in various ways including; water-efficient fire testing systems, efficient plumbing fixtures, provision for water recycling, and xeriscaping solutions.

The efficiency of green buildings does not only offer lower operating costs but it also provides for sustainable building operation. The minimized environmental impacts provide for a reduction in the built environment’s contribution to climate change and the spread of communicable diseases.

Sources:

Green Star SA New Buildings Technical Manual

Renewable Energy Solutions, European Centre of Technology

About the Author Kagiso Sebetso BSc Hons Construction Management, MSc Property Studies, Accredited Professional Green Star SA- New Buildings (GBCSA).

Kagiso is an advocate for green building innovation and education and is a Green Star Accredited Professional through the Green Building Council of South Africa. She is currently involved in facilitating green building strategizes for commercial buildings as part of her career. Kagiso hopes to see Botswana's construction industry take ownership of indigenous and green building technologies that serve the country's environment and energy needs