Optimum performance standards/processes
Successful projects follow performance standards from project start to end.
By Paul Levy, CCxP, Kirlin Mechanical Services, Rockville, Md.
This list focuses on a few of the standards that are often overlooked entirely or that should be examined more carefully.
1. Air Barrier Performance Standard
Controlling the air leakage in buildings is one of the most basic, yet critical, details needed if a building is to have a low energy quotient. Properly detailed and constructed, this one item can reduce the heat load by one-third (See: Westford House, Joe Lstiburek, PhD, Building America, ASHRAE Journal Dec. 2008).
Standard: ASHRAE Standard 90.1-2010, 5.4. The assembly of materials shall not exceed 0.04 cfm/sq ft under a pressure differential of 0.3 in. w.g. (water gauge) when tested in accordance with ASTM E 2357, 1677, 1680, and E283.
This is the amount of window area and the window’s engineering, aesthetic characteristics, and glare to be addressed against an economic sensitivity test of performance versus cost. (See AEDG Implementation Recommendations: Daylighting Window Designs for more details.)
Standard: A lifecycle cost analysis (LCCA) should be performed to balance the heating and cooling impact to the savings from the daylight harvesting.
3. Maximize LEDs
LED lights are most effective in hallways and places where lights operate 24/7 or for the maximum hours of the building occupancy.
Standard: There is no standard provision requiring LED. The best practice is to perform a LCCA to determine the optimal light fixture selection. (See a webinar offered by the Energy Center of Wisconsin for more information.)
4. Roof albedo
Albedo, or solar reflectance, is a measure of a material’s ability to reflect sunlight. A cool roof is one that exhibits high albedo and offers immediate benefits, including reduced energy costs. (See Cool Roof Ratings Council’s “Other Cool Roof Codes and Programs” and the U.S. Dept of Energy’s “Guidelines for Selecting Cool Roofs.”)
Standard: ASHRAE 90.1-2010 part 18.104.22.168.1 with solar reflectance and thermal emittance standards
5. Electrical sizing of conductors
Electrical conductors should be properly sized. Oversizing is a waste of resources with very little, if any, benefit.
Standard: Electrical sizing of conductors shall be designed per NFPA 70: National Electrical Code. Main switch boards and service entrances shall be sized per NEC 2011 for the AIC using information from the utility for the transformer, or if the information is not available, via a calculation based upon the minimum impedance allowed by code.
Resource: Stallcup's Electrical Design Book, 2011 Edition, James G. Stallcup, author.
6. Transformers, based on load factor
Many engineers and owners believe that a dry type transformer with an 80 C rise is more efficient than the 150 or 115 C construction. The best practice is to relate the temperature design rise to the load factor. This small detail can increase the efficiency of a building by 1%.
Standard: Dry type—the design temperature rise of 150, 115, or 80 C shall be based upon the load factor of <35%, <50%, or >50%, respectively. Minimum efficiencies shall be per NEMA TP-1 and EPACT 2005.
Resource: Dry Type Transformers, Codes and Standards Enhancement (CASE) Study, Pacific Gas & Electric, Author: Patrick Eilert.
7. Grounding details, in which all grounds bond together
The purpose is to prepare a design that bonds the grounds to a common point; this will establish a common ground reference. This practice is critical for proper operation of low-voltage controls.
Standard: NEC 2011. All individual grounds shall bond back to a common bus.
Resource: Stallcup's Electrical Bonding and Grounding Simplified NEC 2008 by James G. Stallcup
8. Accessibility to equipment for maintenance
Required clearance and design criteria shall be shown on the contract drawings.
Standard: Equipment shall have accessibility as required by building codes, equipment manufacturer, or the owner's project requirements in the commission plan.
9. Ventilation standard
The basis of design, the control sequences, and the logic necessary to achieve the ventilation requirements will be shown on the drawings.
Per ASHRAE Standard 62.1-2010, the ventilation standards used shall be shown. This shall include the Ev (ventilation effectiveness) values and any adjustments used, for example, charcoal filters, gas measurement, etc.
10. Demand control ventilation (DCV)
Buildings need to be properly ventilated without being wasteful. To minimize over-ventilation, direct measurement of CO2 can be monitored and the outdoor air quantity adjusted to achieve a good balance.
Standard: As required by ASHRAE 90.1-2010 part 22.214.171.124 for high -occupancy areas.
11. Formaldehyde-free materials
Formaldehyde can cause scratchy throats, headaches, and dry eyes. With the proper selection of materials, the source of these issues can be eliminated. Use inorganic materials so mold can’t grow.
Standard: While there is no reference or standard for using formaldehyde-free materials, there is no longer a cost premium for these products.
12. The systems manual
This document assembles the information about the design and operation of the building. As a best practice, the requirements for the systems manual will be in the specifications and will be a deliverable to the owner.
Reference ASHRAE Guide line 0-2005 and ASHRAE Guideline 4-2008.
Paul Levy is a commissioning consultant at Kirlin Mechanical Services. He has 30 years of experience in large, complex mechanical construction system installations and operations, and serves on ASHRAE technical committees.
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