Workplan to Analyze the Energy Impacts of Envelope Airtightness in Office Buildings.
Workplan to Analyze the Energy Impacts of Envelope
Airtightness in Office Buildings.
Emmerich, S. J.; Persily, A. K.; VanBronkhorst, D. A.
NISTIR 5758; 31 p. December 1995.
Sponsor:Department of Energy, Washington, DC
Available from: National Technical Information Service
Order number: PB96-154463
office buildings; air flow modeling; building energy
simulation; building technology; commercial buildings;
computer simulation; heating; ventilation; air
U.S. office buildings consume approximately 1.2 EJ (1.1
Quadrillion BTUs or Quads) of energy, 0.72 EJ (0.68
Quads) of which is associated with space heating,
cooling, and ventilation. These estimates, and other
analyses of energy consumption in office buildings, are
based on building energy analysis programs such as
DOE-2. These analyses have been helpful in identifying
opportunities for energy efficiency, developing building
energy efficiency standards and predicting future energy
consumption levels. Although these programs contain
sophisticated models of heat transfer and HVAC system
performance in buildings, they are acknowledged to have
shortcomings in accounting for the energy associated
with building airflows, particularly infiltration of
outdoor air through leaks in the building envelope.
These airflows, and their dependence on weather and
ventilation system operation, are more complex than the
models used in these programs. The simple models of
infiltration, ventilation and interzone airflows that
are used in these programs do not enable the analysis of
the energy consumption associated with building airflow
or the impact of options that may reduce this energy
consumption, such as increased envelop airtightness or
better control of ventilation system airflow rates.
This report describes the impact of building airflows on
energy consumption in multi-zone buildings and the
analysis approaches that can be used to account for the
energy associated with these airflows. Plans to link a
multi-zone network airflow analysis program with a
building energy analysis program are discussed. An
initial estimate of the energy associated with
infiltration in U.S. office buildings, based on a
simplified analysis approach, is presented. This
estimate reveals that infiltration in U.S. office
buildings accounts for 0.074 EJ (0.07 Quads) of space
heating energy use, which is 18% of the total heating
energy use, and 0.0025 EJ (0.0024 Quads) for cooling,
which is 2% of the total.