The built environment generates 47% of global CO2 emissions, 27% from building operations, and an additional 20% from embodied carbon in building material and construction. Reducing CO2 emissions from the built environment is critical to addressing climate change.
Winners of the COTE® (Committee on the Environment) Top Ten Awards from the American Institute of Architects use sustainable design fundamentals to lower emissions that are essential for winning awards. But equally important, they are critical to every new construction, remodeling, and upgrade of buildings. Here’s a closer look at five fundamental ideas that have been used in many of these projects.
#1 Integrated Design
Integrated design, as its name suggests, integrates perspectives from architects, engineers, the client, and other stakeholders to identify opportunities to reduce environmental impact. It provides for coordination of the components of a building such as site, structure, systems, and ultimate use. The collaborative effort tackles architectural decisions, engineering considerations of materials and construction, water resources, energy requirements, and the effects of the building on the ecology and community.
For example, the facility at 663 South Cooper converted a parking lot into a courtyard that supports multiple uses: a place to plant trees, a location for the geothermal field, an infiltration field to improve stormwater management, and outdoor space for occupants.
#2 Energy Efficiency and Renewable Energy
Energy efficiency, using the least possible amount of energy to create comfortable living conditions, along with using renewable energy sources is part of the solution to reducing emissions from the built environment. Using Passive Design principles – sunlight and natural ventilation to efficiently heat and cool places – is a great start to energy efficiency. In addition, it requires making thoughtful decisions in many aspects of the building including the building envelope, roof, windows, lighting, and the type of heating and cooling systems. Each choice is an important tool and is covered in detail in later sections. Onsite renewable energy options include solar panels for electricity, geothermal energy for heating, and solar water heaters.
The dramatic solar panel canopy that cascades to the south entrance at Edwin M. Lee Apartments in San Francisco is a great example of onsite renewable energy.
#3 The Building Envelope and Insulation
The building envelope, which includes the walls, windows, roof, and foundation, provides the thermal barrier between the interior and exterior environments. Air barrier solutions, like sealants, membranes, spray foams, and sheathings, help seal any leaks and prevent conditioned air from escaping to the exterior.
Windows have a dual role to play, letting in natural light and providing thermal comfort. Double or Triple pane windows are options. Triple pane windows add a combination of gases like krypton and argon in between three layers of glass to provide increased thermal insulation. Another hi-tech option is smart glass or electrochromic glass, which enables control of the amount of visible light and heat entering a space by sending an electric charge through the glass that lightens or darkens the glass as needed.
Green roofs use vegetation and soil as insulation; cool roofs reflect sunlight to reduce the energy needed for cooling. Roofs also make excellent locations for solar panels used in onsite energy generation.
The Louisiana Children’s Museum uses an integrated design approach using passive design elements with a better-than-code-minimum building envelope. Light-colored exterior walls and low albedo roof panels help to reduce solar absorption and minimize the local heat island effect.
#4 HVAC and Lighting & Building Automation Systems
A large part of the energy consumption in a building is from the heating, ventilation, and air-conditioning (HVAC) systems followed by energy needed in lighting.
Several new technologies are available to replace the older HVAC and lighting systems. LED lighting uses much less energy than older incandescent lighting. Heat pumps that use electricity and work on the principle of harvesting heat from their surroundings are alternatives to older HVAC systems. Air-source heat pumps transfer heat from the surrounding air and geothermal heat pumps transfer heat from the earth.
Building Automation Systems are a combination of sensors and programmable controls that optimize the operation of HVAC, ventilation, and lighting systems based on occupancy patterns. They can also be used to detect equipment failures or inefficient operations. Research at the Department of Energy has shown an estimated saving of 29% in energy consumption. A bonus is that these systems can be used to decrease peak loads on electric grids, a solution that plays a key role in decarbonizing electric grids.
The King Open/Cambridge Street Upper Schools & Community Complex uses ground source heat pumps with 190 geothermal wells supplying radiant heating and cooling.
#5 Water efficiency
While not directly related to emissions, using water efficiently is important for making buildings more resilient to climate change. Indoor water use can be monitored with smart meters and high-efficiency fixtures can be used to reduce water use. Outdoor water usage can be reduced by using locally adapted plants, efficient irrigation, harvesting rainwater, and recycling gray water for irrigation. Mimicking natural hydrology and reducing impervious surfaces to allow for natural drainage are important to flood control measures.
The Meyer Memorial Trust Headquarters design converts a brownfield site into a garden campus that uses a native and adaptive plant palette and manages 100% of stormwater.
Our ability to avert the climate crisis depends on our ability to reduce emissions from the built environment. If you are looking at your next remodeling, maintenance, or HVAC upgrade, take the above considerations seriously. I most definitely will. They may not lead to awards but will give us and future generations the best award: a greener, sustainable planet.
Images from the COTE® (Committee on the Environment) Top Ten Awards website
