Looking to the Future: Net-Zero Energy Buildings

Looking to the Future: Net-Zero Energy Buildings

By Hugh McMillan

For the Design/Build contractor, it’s important to understand the direction the construction industry is headed. The federal government is leading the energy conservation movement and has enlisted the help of organizations such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the U. S. Green Building Council USGBC, and the American Institute of Architects to write energy conservation standards intended for use by code bodies.

If we understand the direction of the industry, we can plan to get ahead of the curve and provide leadership, and ultimately take ownership of the issue. This will allow us to drive the standards and design guidance in ways that are useful to our industry and not mandated by the federal government.

Speaking of the federal government, it has, by Executive Order, required each of its agencies to reduce the energy use intensity of its buildings by 3% per annum, or 30% by 2015. Agencies mostly met earlier targets culminating in a 30% reduction between 1985 and 2005 based on legislation enacted in 1992. In response to this initiative by the federal government, the private sector has brought forward several initiatives designed to drive energy conservation forward, culminating in net-zero energy buildings by the year 2030.

The Vision of Net Zero
The vision of a net-zero energy building is to collect as much energy from renewable sources as the building uses on annual basis, while maintaining an acceptable level of service and functionality. Buildings can exchange energy with the power grid as long as the net energy balance is zero on an annual basis.

The intent of net-zero energy buildings can be defined using several metrics. Among these are site energy, source energy, emissions, and energy cost. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has recommended, through its Vision 2020 report, that site energy be the basis for net-zero energy buildings in its standards and design guides. Architecture 2030 recommends emissions as the basis. Whatever the basis, with federal government buildings targeting energy use reductions and many of our construction industry organizations developing standards for use by code bodies that will mandate energy use reduction, it’s important that all of us take a look at the tools that are currently available and that are planned to move to net-zero energy usage in buildings by 2030.

Energy Conservation Tools
ASHRAE is developing many of the tools that will be useful to system designers and builders moving forward to the target date. In response to the federal government’s mandate that its buildings reduce energy usage by 30% by 2015, ASHRAE President Terry Townsend called for its Standard 90.1-2010, Energy Standard for Buildings Except Low-Rise Residential Buildings, to be 30% more stringent than a baseline energy usage represented by Standard 90.1-2004. The ASHRAE Board of Directors approved the following energy reduction targets in March of 2007:

The year shown in the table is the year in the three year publication cycle in which ASHRAE will publish its energy conservation standard. Since ASHRAE, the Illuminating Engineering Society of North America (IESNA), and the USGBC are jointly developing a high-performance green building standard (Standard 189P), it’s possible that that standard may be the vehicle that will take energy conservation to net-zero energy usage by 2031. If that’s the case, Standard 90.1 would remain the standard for minimum energy code compliance.

Preceding the 30% reduction anticipated in Standard 90.1-2010, ASHRAE has published a series of design guides that show paths to 30% energy reduction in buildings. While the baseline for comparison is different, if the guidance is followed, significant energy reduction will be realized. These Advanced Energy Design Guides show paths to energy reduction in small commercial office buildings and small retail spaces (less than 25,000 sq.ft.).

Anticipated to be complete and available in early 2008 are 30% Advanced Energy Design Guides for Warehouses and for K-12 Schools. It’s important to note that the 30% design guide series only shows one possible path for compliance for each climate zone.

Currently under development by ASHRAE are a series of 50% energy reduction design guides. Guides will be developed for both new and existing buildings, will show multiple compliance paths and will be climate zone based. These guides are anticipated to be available by 2010.

After the 50% design guides are published, the final series of design guides will be developed. These guides will target a 70% energy efficiency improvement for new and existing buildings. It’s anticipated that this improvement approaches the reasonable limit for energy conservation in buildings. To reach net-zero energy usage, the balance of the energy used will have to be supplied by on-site renewable energy sources.

This last series of Advanced Energy Design guides will not only show multiple compliance paths for new and existing buildings, but will also provide design guidance for on-site renewable energy sources. This last series of guides are anticipated to be available in 2015.

Net Zero and Design/Build
Awareness of the issues surrounding energy conservation and knowledge of where we are headed can be useful with our clients. Sophisticated building owners will be well aware of where energy conservation is headed, and will seek to develop relationships with contractors who can work as partners with them. By demonstrating an awareness of where energy conservation is headed in both the near-term and the long-term, and providing economically viable solutions that optimize the first cost/life-cycle cost balance for energy conservative systems, you can become that partner.

By continuing to stay ahead of the curve as new equipment, systems, design techniques and building materials are developed, your chances to develop relationships that lead to repeat business are magnified. And to benefit the industry as a whole, consider actively participating in the organizations that are developing these standards and guides.

Hugh McMillan is a senior mechanical engineer in the Houston office of ccrd Partners. He has more than 30 years experience in the HVAC industry in mechanical system design and sales, and temperature control system design and installation. He is a registered P.E. Texas, Maryland and Louisiana. Mc- Millan is a past vice-president of ASHRAE, chair of the Technology Council, and also served on the ASHRAE Board of Directors as director and regional chair for Region VIII. He can be reached at 713/237-8900, e-mail [email protected]

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