Outcome-based approach to building energy

这类基于结果的建筑设计方法和operation can provide a path to energy-efficient buildings. For several years, under the leadership of the National Institute of Building Sciences (NIBS), representatives from across the building industry, including code officials, building owners, manufacturers, designers, and energy-efficiency advocates, have come together to develop a new “outcome-based pathway” approach to meeting energy-efficiency requirements.

I was fortunate to represent ASPE on the development committee for the International Green Construction Code (IgCC) that reviewed the new proposal and approved it on May 4. (See nibs.org/news/172233/New-Approach-to-Energy-Code-Compliance-Clears-Major-Hurdle.htm.) If adopted into the IgCC in October, this will be the first outcome-based compliance path in a model energy code.

The building industry has set a goal to construct facilities that use less energy and water while providing a safe indoor environment for those in the building. The ultimate goal is for buildings to be less harmful to the environment outside the building. But, the industry has discovered that reaching this goal can be a complex and difficult process.

The industry has identified six major building professionals who need to work together to reach this goal. They are the designers, manufacturers, contractors, owners, operators, and regulators. All six of these groups should work as a team to reach this goal of efficient buildings. Only when they work together can this objective be obtained. For example, the plumbing engineer can design important parts of an energy- and water-efficient building, but if the building operators do not maintain and operate the systems as they are designed, the building will not reach its efficiency goals.

每个建筑专业需要一个过程, guideline, or set of regulations to follow to reach this goal. The USGBC is one organization developing processes for building professionals to reach efficiency goals. Following the LEED guidelines during design can help, but that does not guarantee that the building will operate efficiently. The IgCC is another process that building professionals can use. It is a code-based approach that communities can adopt to help building regulators develop a method to produce efficient buildings.

Up until now, green building programs, such as LEED and the IgCC, have used a prescriptive path or a performance path. The prescriptive path has been used primarily for smaller buildings. The concept is simple: installing efficient systems will result in an efficient building. Those of us in the plumbing industry know that installing water-efficient plumbing fixtures can reduce water and energy usage in a building. For example, a 1.5-gallons-per-minute (gpm) showerhead will use less water than a 2.5-gpm showerhead for the same duration. However, if the shower is not used enough to make any significant water or energy reductions in the building, the end result is that the building team did not reach the goal of an efficient building.

The performance method models the building using different efficient systems to produce an efficient building. This method compares different systems in cost and operations to help the design team decide which systems are a good match for a building. While the performance method is considered more accurate than the prescriptive method, it does not always result in efficient buildings. For example, what if the 1.5-gpm showerhead was replaced with a 2.5-gpm showerhead because the maintenance personnel didn’t know the difference? The end result is an inefficient building.

Other building market forces are setting goals to have carbon-neutral or net-zero buildings by 2030. Unfortunately, current codes and standards will not help buildings meet the 2030 challenge. Another issue is the availability of products that will be on the market to reach the 2030 challenge. If only a limited number of products are available to help reach the goal, the concept of the goal can be compromised.

Outcome-based path

The outcome-based method is a third pathway that links with the 2030 challenge while working with industry and regulators to develop a process to help the entire team work together to reach efficiency goals. It is based on actual building performance data while the building is operating. Designers have been an important part of its development, and manufacturers are setting goals to provide products that will be on the market to help buildings meet their efficiency targets. For example, the method will list higher efficiency ratings for pumps. The pumping industry is supporting the outcome pathway and will have products available for buildings wanting to meet these requirements.

New technologies are available in the plumbing industry, such as efficient pumps and innovative water heaters. The problem is that many of the criteria used in existing energy codes do not allow for the application of new technologies, so buildings cannot establish an actual Energy Use Intensity (EUI), which is how Energy Star benchmarks buildings. Essentially, the EUI expresses a building’s energy use as a function of its size or other characteristics. The outcome-based pathway will help provide a methodology for measuring and expressing the energy use of a building using these new technologies. Thus, it will be easier to compare the technology target reference EUI as part of the compliance verification process.

The outcome pathway is based on different building types in different climate zones. Thus, the energy and water usage from one climate zone will not be compared to another building in a different climate zone. Those opposing the proposal were concerned that not enough data is available for the different types of buildings in each climate zone. Supporters responded by saying enough data is available now, and over time more data will be available to fine-tune the requirements.

This is a radically different approach, and it is worth asking if it will be accepted. Supporters say that this method is a more flexible pathway that will result in measurable results. It is needed to build net-zero energy buildings. As time goes by, more real-world data will be available on actual energy usage in buildings, and compliant buildings should be worth more than noncompliant buildings.

Some are concerned that if this approach is accepted by the IgCC and becomes code, it will be the only approach available for green buildings. It is important to remember that the IgCC does not require this approach. The prescriptive and performance paths are also available options. While the IgCC is not adopted in many areas of the country, adding the outcome-based pathway will strengthen the code, so more jurisdictions should want to adopt it. Communities that want to take an aggressive approach to efficient building will find this code attractive. However, jurisdictions that want to adopt the IgCC but have reservations about the energy section have the option not to adopt every part of the code.

Another concern is violations. What will happen to buildings that do not pass the test after one, two, or three years? Can a building lose its certificate of occupation? These are questions for local jurisdictions to determine what works best for them.

This is an important shift in our industry. I will cover more details on the outcome-based pathway in future articles.

Winston Huff, CPD, LEED AP BD+C, is a senior project manager, plumbing fire protection designer, and sustainable coordinator with TRC Worldwide Engineering, Inc. He serves as an ASPE representative on the ICC Green Construction, Energy, and Water Code Development Committee and is on the U.S. Green Building Council’s Water Efficiency Technical Advisory Group. He was the founding editor of Life Support and Biosphere Science and has served as its editor-in-chief. He is also the editor of Me Green You Green, a LEED credit databank atwww.megreenyougreen.com.