Technologies for measuring flow rates of outdoor air into HVACsystems: Some causes and suggested cures for measurement errors

Journal Article · Mon Nov 01 04:00:00 EST 2004 · ASHRAE Transactions

OSTI ID:881724

Fisk, William J; Faulkner, David; Sullivan, Douglas P

Although the rate of outdoor air (OA) ventilation has a substantial influence on building energy consumption and occupant health, the available data indicate the outdoor air ventilation rates are poorly controlled in many buildings. Technologies being marketed for real time measurement of the flow rates of outdoor air into HVAC systems should enable better control of OA ventilation. In laboratory research they have studied the performance of these technologies. Sources of measurement errors identified during conduct of this research include: low air speeds; high spatial variability in air speed and direction; large eddies downstream of outdoor air intake louvers; and backwards airflow through a portion of outdoor air dampers. Several suggestions for overcoming these sources of errors were developed including: design and control of the outdoor air intake system to avoid low, hard-to measure, air speeds; use of highly sensitive pressure and velocity sensors; measuring air speeds between blades of louvers, rather than downstream of louvers; smoothing out the airflow between the outdoor air louver and damper through proper louver selection and insertion of components to straighten air flow; and maintaining a pressure drop across the outdoor air damper that exceeds approximately 0.04 IWG (10 Pa).

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE. Assistant Secretary for Energy Efficiency andRenewable Energy. Office of the Building Technologies Program
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 881724
• Report Number(s): LBNL--56604; BnR: BT0201000
• Journal Information: ASHRAE Transactions, Journal Name: ASHRAE Transactions Journal Issue: pt2 Vol. 111; ISSN 0001-2505; ISSN ASHTAG
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
AIR FLOW
DESIGN
ENERGY CONSUMPTION
FLOW RATE
HVAC SYSTEMS
OCCUPANTS
PERFORMANCE
PRESSURE DROP
TIME MEASUREMENT
VELOCITY
VENTILATION