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CODES AND STANDARDS

Building codes and standards continue to drive requirements for increased outdoor-air ventilation rates. Engineers and building owners will want to pay special attention to:

• Standard 62.1, which sets minimum ventilation rates and other requirements for commercial and institutional buildings. Leadership in Energy and Environmental Design for New Construction and Major Renovations Green Building Rating System requirements can exceed Standard 62.1 ventilation rates by up to 30 percent.

• Standard 90.1, which mandates air-side energy recovery when supply-air capacity is 5,000 cfm or more, minimum outdoor air is 70 percent or more, and system effectiveness is 50 percent or more.

  

  A proposal to improve upon American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) requirements by addressing specific climate variations within the United States is being considered. The proposal, referred to as Addendum e to Standard 90.1-2007, has gone through the public-review process and is on the agenda for publication approval during ASHRAE's 2010 Winter Conference in January. The proposed enhancements are shown in Figure 3.

• Proposed ASHRAE Standard 189.1, Standard for the Design of High Performance, Green Buildings Except Low-Rise Residential Buildings, which mandates energy recovery, including outdoor-air rates as low as 10 percent of total supply air (Table 1).

• 

  The 2006 International Energy Conservation Code, which includes language from Standard 90.1 as it relates to supply-air fan systems and energy-recovery requirements.

SUMMARY

DOAS provide a straightforward, energy-efficient approach to handling ventilation air. The use of energy recovery, supply-air conditions, supply-air delivery location, and sequence of operation are important to maximizing annual energy savings and comfort.

Incorporating air-to-air total-energy-recovery devices into DOAS can reduce the energy needed to cool and heat ventilation air significantly. The technology is cost-effective, with payback periods ranging from less than one year to three years for most applications.

Codes and standards are mandating ever-more-energy-efficient HVAC systems and technologies. Engineers and owners must stay abreast of these developments to ensure not only compliance, but that the economic benefits of specifying optimal equipment are realized.

REFERENCES

1. Mumma, S.A. (2007, August). DOAS & desiccants. Engineered Systems.

2. Greenheck. (1999). Energy recovery ventilators: The engineer's solution (ERA/100-00). Retrieved from http://www.greenheck.com/library/articles/19

3. Murphy, J. (2006, July). Smart dedicated outdoor air systems. ASHRAE Journal, pp. 30-37.

4. Greenheck. (2007). Optimizing dedicated outdoor air systems (ERA/114-07). Retrieved from http://www.greenheck.com/library/articles/79

The general manager of tempered-air products, Mike Wolf, PE, has been with Greenheck for 23 years, during which his responsibilities have included engineering, manufacturing, marketing, and sales. He is a past chairman of Air Movement and Control Association International's HVAC Fire & Smoke Damper Engineering and Air Control Engineering committees. Jackson Smith is a senior application engineer within Greenheck's tempered-air-products group. His HVAC focus is on building ventilation, with an emphasis on energy recovery.