Using less is one of the key concepts of sustainability. Conserving energy, diverting waste from landfills and reducing the consumption of raw materials are core components of what “green” means to businesses and consumers today.
But how much is less? If saving energy is good, wouldn’t not using any energy be better? As regulators and consumers become more sophisticated, building designers have found that the cutting edge has moved past using less and on to shooting for zero.
Net zero is a framework that asks if a building can produce as much as it uses. The question can be asked about energy, water and even the waste materials generated by a building. For most buildings, using zero is quite difficult – but the concept of net zero now defines the leading edge of environmentally-conscious building design.
The greenest building in the United States is set to open in a few short months, and these ideas are at the core of its design. The Bullitt Foundation, an environmental non-profit, has adopted two particularly ambitious goals for the new Bullitt Center in Seattle: 100 percent of energy will be generated by on-site renewable sources and 100 percent of water will be provided by captured rainfall.
The idea of self-sufficient buildings has inspired the design community for decades, but the earliest net zero buildings were small, in favorable climates and low energy-intensity building types, such as houses. But an increasing number of projects are seeking to meet the net-zero challenge at larger scales.
The U.S. Department of Energy’s National Renewable Energy Laboratory played a key role in proving the feasibility of net-zero buildings. NREL’s Research Support Facility was carefully designed to minimize the traditional energy demands of an office building. Photovoltaic panels were installed at the rooftop and a few other locations on site to meet the goal of completely offsetting the RSF’s energy consumption.
Pursing net zero requires smart design. A conventionally designed building paired with a gigantic solar array might be net zero but the cost of such a project would be unfeasible.
Instead, designers work to minimize the costs of making a project net zero. For example, buildings can optimize daylight from windows while making use of shading and overheads to avoid solar heat load during the summer. With the heat from electric lighting and solar loads reduced, smaller cooling equipment can be selected. HVAC and other equipment (think computers or appliances) must be as efficient as possible. The outcome of load reduction and efficiency in meeting loads is a reduced need for renewable energy.
Whether dealing with energy, water or waste, a net zero design process follows a similar process. Design teams have to ask themselves:
- What are our local resources, and how can we draw on them?
- What demands are we creating?
- Can we reduce those demands?
- Can we meet the remaining demands more efficiently?
- Can we bring our demands in line with our resources?
The implementation of net-zero design can take a variety of forms depending on the project. The New Buildings Institute’s Getting To Zero program assembles design recommendations and case studies from net-zero buildings across the United States. The NBI also collects information on the extra costs associated with net-zero design. For the program’s 2012 update, NBI found the incremental costs of energy efficiency measures to be between zero and 10 percent.
An aggressive early adopter of net-zero thinking might surprise you. The U.S. Army has set a goal for 18 bases to achieve net zero in energy, water or waste by 2020. Two facilities, Fort Carson in Colorado and Fort Bliss in Texas, will target triple net zero.
The Army has acknowledged that the benefits of net zero extend beyond eliminating energy bills or trash cans. Recent events such as the Fukushima nuclear disaster and recent severe hurricanes have underscored the need for resiliency and independence in the built environment. In this context, net-zero design becomes more than just a metric or points on a score card; net zero becomes essential to understanding how a building relates to its environment and a vital tool for pursuing real sustainability.