Paper 2: Volume 3 No.4 March 2005 Edition
1,
2, 3B. J.
Wachenfeldt and 3P. O.
Tjelflaat
1SINTEF Technology and Society, Architecture & Building Technology,
7465 Trondheim, Norway
2Norwegian University for Science and Technology, Dept. of Architectural
Design, History and Technology, 7491 Trondheim, Norway
3Norwegian University for Science and Technology, Dept. of Energy and
Process Engineering,
7491 Trondheim, Norway
Abstract
In order to study the energy
performance of a school building incorporating a hybrid ventilation system in
Grong, Norway, a detailed field experiment was carried out. Total airflow rate
and pressure differentials over the various components, ducts and openings in
the ventilation system were accurately measured in situ, and empirical
relations describing their pressure characteristics were derived from the
measurement results. These empirical relations were then implemented into a
computer simulation tool incorporating an inter-zone airflow network model for
detailed analysis of the building’s dynamic energy performance.
The total pressure drop for the
ventilation system was derived as ∆p=29.1Q+2.3Q2
Pa, where Q m3/s is the
airflow rate. When all the fans were operating at maximum power, the airflow
rate was measured as 2.3 m3/s, while the rate for normal daytime
operation was between 0.2 and 1.7 m3/s. The relation therefore
suggests that laminar friction dominates the flow resistance, although loss of
velocity head due to viscous dissipation becomes increasingly important as the
airflow rate approaches the capacity limit.
Pressure characteristics measurement results for
components, such as air filters and heat exchanger units, show that components
made for traditional mechanical ventilation can readily be used in a hybrid
ventilation system. However, there is a demand for performance data at face
velocities down to about 0.2 m/s.
Key words: hybrid
ventilation, case study, ventilation components, pressure differentials, airflow
rate, energy performance.
References
Tjelflaat PO: (2002)
“Pilot Study Report:
Mediå
School
,
Grong
,
Norway
”, IEA ECBCS Annex 35: HybVent,
Univ.
of
Aalborg
,
Aalborg
.
Wachenfeldt
BJ: (2003)
”Natural ventilation in
buildings, detailed prediction of
energy performance”, Department
of Energy and Process Engineering, Faculty of Engineering, Science and
Technology, NTNU, Dr.
ingeniøravhandling (PhD thesis) 2003:72.
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IJV Volume 3 No 4
Contents
Paper
1: Case Studies
Paper
2: Field Measurement
Paper
3: Pre-Heat Window
Paper
4: Buried Pipe
Paper
5: Plane Jet
Paper
6: Centrifugal Blower
Paper
7: Simplified Model
Paper
8: Thermal Comfort
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