By Diana Gutierrez, M.S. Civil Eng., LEED AP BD+C, Senior Sustainability Specialist
Energy efficiency is good for the environment, but more so it is an important cost saving component for any business, facility management or homeowner’s budget. On an annual basis, commercial buildings in the U.S. consume 68% of America’s electricity and 39% of its total energy. Without even mentioning that these same buildings generate 38% of our greenhouse gases, one can easily see that the low hanging fruit in the building industry is energy efficiency in new and renovated buildings. It is important to note that it is possible to achieve energy efficiency while maintaining a project budget.
For a new or renovated building to achieve energy efficiency, make sure to include these three steps:
- Use a comprehensive integrated design process, also called Integrated Project Delivery
- Establish goals, targets, and strategies
- Implement energy efficiency measures holistically
The key to energy efficiency in new buildings or renovations is to have a comprehensive integrated perspective during the design phase that seeks to:
- Reduce heating, cooling, and lighting loads through taking advantage of the building site and climate attributes. Include passive solar design and integrated landscape design that use trees for shading, windbreaks, and attractive outdoor spaces.
- Research and include renewable energy sources such as daylighting, passive solar, solar thermal (hot water) and photovoltaics, and geothermal heating and cooling. Use of renewable energy increases energy security and reduces dependence on fossil fuels.
- Use project specifications to lay the groundwork for energy efficiency, specifically stating project goals, targets, and strategies for energy efficiency. Specify energy efficient HVAC equipment that meet or exceed federal, state, and local standards, such as ASHRAE 189.1, Energy Star, or other federal or state high-performance mandates.
- Increase building performance by including predictive energy models and system controls, such as occupancy and daylight sensors, CO2 sensors and other air quality alarms. Employ sensors that control loads based on occupancy and availability of natural resources such as daylight or natural ventilation. Use energy management tools to track energy and water use such as the Energy Star Portfolio Manager.
- Integrate water saving technologies that reduce the energy burden that comes along with providing potable water such as WaterSense fixtures and rainwater harvesting practices.
- Measure and verify that the predictive model and energy efficiency goals were met.
A sustainability design charrette is a good way to involve the team early on to set broad sustainability goals. The next step is establishing whole building performance targets that take into account the intended use, occupancy, operations, plug loads, and other energy demands. Doing this will put you on a path to achieve energy reductions from baseline established codes and standards. Achieving an Energy Star rating is a performance target that puts a project in the top 25% of all buildings of its type for energy efficiency, well above what is required by code. Another common project goal is to reduce a project’s energy use to 10, 20, or 30% below the applicable energy code. Codes are set as a minimum requirement, and today’s projects can easily achieve higher levels just by starting early and including energy goals from the start.
The U.S. Green Building Council’s LEED (Leadership in Energy and Environmental Design), Green Globes and other rating systems provide a blueprint that includes energy efficiency along with site, water, and materials efficiencies. Green rating systems provide the standards and measures to help to define what a sustainable building is.
To achieve energy efficiency goals take a look at individual Energy Efficiency Measures or EEMs. The goal of EEMs is to achieve reductions in energy and utility costs. Here is a list of some common EEMs. When these are considered as a group, and early in design, the best combination of EEMs can be determined to meet the sustainability goals and the project budget. Here is a list of some of the most important measures to consider: Solar orientation, wall insulation, windows, solar shading, light shelves, daylight controls for dimming, ground source heat pumps, underfloor air plenum, demand-controlled ventilation, and energy recovery ventilation units.
Simple paybacks on EEMs can be determined for individual and/or combined EEM strategies by including these measures in an energy model. The energy model will calculate annual energy savings relative to the associated costs for the proposed EEMs. The most efficient combination of EEMs above can reduce the overall HVAC system load by up to 40%.
The goal of using green building principles to support energy efficiency in new buildings and renovations is to create high performance buildings that have limited environmental impact and the lowest possible life-cycle costs.