- Bill Starkey
Can Green Buildings Really Reduce City Temperatures by Two Degrees?
With the global construction industry accounting for somewhere in the region of 36 percent of final energy use and 39 percent of total CO2 emissions, the impetus to make construction greener and more sustainable has never been greater.
Reducing carbon emissions has multiple global benefits. Climate change is humankind’s gravest threat, as global temperatures have already increased by 1 degree Celsius since the preindustrial period. It’s expected to rise by up to 3.7 degrees Celsius by the year 2100 under current policies.
Carbon emissions remain in the Earth’s atmosphere for up to a century, and up to 80 percent dissolves into the seas over 20 to 200 years. This crisis not only impacts the environment but also the economy, with evidence suggesting that reducing carbon emissions would benefit the global economy.
How Green Buildings Can Help
Green buildings are not only vital in the fight against climate change, but they also have significant social benefits, such as improving the health, wellbeing, and productivity of building occupants. Research suggests that green buildings can have the same benefits in terms of health and wellbeing as spending time in nature, which is particularly beneficial to people living in cooler climates. One study even suggested that patients in green hospitals heal more quickly.
A 2018 review of 127 papers suggested that physical environmental factors could directly influence or contribute to health outcomes. According to the review, aspects such as visual, thermal, acoustic, and air quality can all have an impact on recovery.
Studies also suggest that a relaxing atmosphere in health facilities can reduce depression and anxiety. While a lack of background music, pictures on the wall, or beautiful exterior views does seem to compromise health, research suggests that they can all have a significant positive outcome on patient wellbeing and clinical outcomes.
Today, we recognize the significant energy-saving benefits of green buildings. They consume less energy, water, and other precious natural resources, and in many cases, green buildings produce their own energy. They also increase biodiversity and reduce the urban heat island effect, a phenomenon created by a combination of dense population, heat-retaining structures, waste heat from buildings, and other human factors. Artificially elevated temperatures in city centers only exacerbate the problem, forcing inhabitants to use even more energy to try to improve ventilation or lower the temperature in their area.
What Do Green Buildings Look Like?
Green buildings often incorporate green walls, green interior decoration, or green roofs; they may be surrounded by green infrastructure. These buildings often utilize grass, algae, vegetables, herbs, or other leafy or micro-green plants in interior or exterior surfaces, which can have a considerable impact in terms of reducing a building’s energy demands. For instance, covering the roof of an uninsulated structure with plants can reduce its winter energy demands by up to 5 percent; in the summer, a green roof can diminish the need for cooling by an impressive 33 percent. Green roofs also reduce indoor temperature fluctuations in the absence of air conditioning.
Green buildings do have some disadvantages. For instance, they cost up to 10 percent more to construct than conventional buildings. Some planners may worry about the added construction and design costs associated with a green building. However, detailed analysis suggests that this nominal increase in cost is worth it in the long term, as it drives down energy bills and provides noticeable benefits for building occupants and those living nearby. In addition, experts believe that green building envelopes could be the key to lowering temperatures in cities.
What Is a Green Building Envelope?
The building envelope refers to a structure’s roof, façade, and other areas that connect the inside to the outside, representing 20 percent to 25 percent of a building’s total external area. Even in the hottest summer, interventions like green roofs help temperatures stay within ambient levels. By contrast, a conventional roof can be up to 50 degrees hotter.
A green envelope can be added to a building’s exterior retrospectively, presenting an economically viable way of transforming the long-term performance of an urban built environment. Adaptations can take many forms, from roof gardens that replace lost urban green spaces to living walls that lower temperature while shielding occupants from noise and sunlight.
According to the World Economic Forum, green buildings could potentially reduce city temperatures by up to 2 degrees Celsius. Another key benefit of embracing green buildings in cities is improved air quality. Indoor air pollution ranks among America’s top 5 environmental public health risks, according to the Environmental Protection Agency. High levels of nitrogen dioxide, sulfur dioxide, airborne microbes, and particulate matter all contribute to serious respiratory illness.
With such a strong case for green buildings, developers are increasingly making sustainability a priority. They benefit from reduced operational costs and increased asset value while simultaneously contributing to the health and welfare of building occupants and improving the lives of those living and working in the local community.
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