large scale climate simulator
The Large Scale Climate Simulator provides controlled conditions of
temperature and humidity above and below test sections as big as 12.5
ft by 12.5 ft. A test section is assembled in a platform outside the
LSCS and moved by a crane. The assembly can weigh as much as 10 Tons
and can be 6 ft high. A low-slope roof test section is shown being
placed in the LSCS in the above photograph, and the residential attic
test section is shown below. Once a test section is in place with all
instrumentation installed and checked out, an automated data acquisition
and control system maintains desired conditions above and below it and
records the responses of thermocouples and resistance temperature devices,
heat-flux transducers, relative humidity sensors, mass flowrate meters,
load cells, current shunts or any transducer that produces a voltage output.
A sketch of the entire LSCS is shown below. The climate chamber simulates any outdoor
condition of interest: steady-state temperatures from 150ºF to -40ºF and a wide range of
relative humidities (dewpoint temperature is controllable from 37ºF to 122ºF). Infrared
lamps can heat surface temperatures to 200ºF. There is sufficient heating and refrigerating
capacity to vary the simulated outdoor conditions in diurnal cycles, which allows tests of the
dynamic response of test sections.
The guard chamber temperature can be controlled from 40ºF to 150ºF and its dewpoint
temperature can be controlled over the same range as in the climate chamber.
With the metering chamber lowered, the guard chamber provides steady temperatures
and relative humidities to simulate indoor conditions below multiple panels,
typically four to nine rectangular-shaped constructions. Construction features
of the panels can be varied and the effect of different features tested simultaneously.With the metering chamber in place against the bottom of a single panel test section,
temperatures from 40ºF to 150ºF can be held below the 8 ft by 8 ft metered area. Such a
large metered area allows details of actual roofs to be tested. For example, the effects of
thermal bridging caused by wood or metal roof structural members can be measured. The heat
flow across the metered area is determined by an energy balance on the metering chamber.
Its precision has been documented to be better than +/-3% and its bias less than 5%.Test sections built for the LSCS have included one comprising four different low-slope roof
sections for simultaneous tests. One of the panels had large reflective cavities as its
insulation configuration. Two nine panel test sections had two different constructions and
four different vapor retarder systems. Water was added and weighing the components of each
panel showed how much water escaped from each. A later six panel test section for studies
of drying rates had each panel balanced on load cells to document the rate of loss of weight.
A multiple panel test section is planned to explore concepts for self-drying low-slope roofs.
The residential attic test section shown in the photograph above was used to test various batt
and loose-fill insulations separately.
Later a duct system was added to determine its effect on conditions in a
residential attic. Half the top of an actual manufactured home and half of a
full-sized steel-framed attic were other test sections to measure the effect of
the interaction between the ceiling and wall at the eave edge. We also studied
extensively the center of steel-framed attics away from the edges. An interesting
use of the Large Scale Climate Simulator was to provide winter and summer conditions
while measuring local temperatures along a small length of electricity transmission
line (shown below). During the tests the line carried up to 1750 amperes of current.
The infrared lights simulated solar load. The extra fans were placed behind the enclosure
to provide a slight breeze over the transmission line.
This page updated on April 10, 2001 by Diane McKnight.