Project: The Museum of Anthropology
(Objectives) (Background) (The Architect) (Museum Sequence) (Systems)
(Long Term Measurements) (Conclusion) (References)
Long Term Measurement - Part 1: An Overview
"Hobo" sensors from Onset Computer are small
enough that they can be unobtrusively placed in a variety of building locations.
In order to collect illuminance, temperature, and humidity data over extended periods of
time, the team used Onset Hobo data loggers. These
sensors are small devices which were launched using a software package called Logbook,
which comes with the sensors. Launched during one visit to the museum, the sensors
collected data every 15 minutes over a period of two and a half weeks. Stored within the
datalogger, the data were downloaded on a subsequent visit. We have serious reservations
as to the accuracy of the illuminance sensors, and therefore to the validity of the data
they collected. These sensors are not color-corrected and therefore, do not respond to
light the way the human eye does. Also, they have consistently measured far less
illuminance than we would expect from a comparison with measurements taken with hand-held
instruments. Lastly, it seems that the sensors respond differently to daylight than to
electric light, but we are unsure what that difference is. Therefore, the illuminance
graphs shown in this report should be looked at as a documentation of relative trends
rather than as absolute intensities.
Hobo (TM) sensors were place on the roof, in a section through the Great Hall, and in a
section through the Masterpiece gallery. These sensors gathered data from February 19
through March 8 (a typical winter period) and again from April 2 through April 21 (a
typical spring period). The amount of data collected was too great to include all of it in
this report, so only a select portion of it will be discussed here. Graphs of the entire
data set can be found in the Building Dossier. The sensors on the roof provide a baseline
against which to compare data from inside the building.
Winter Temperature: Roof sensor
The winter period temperature averaged about 40 deg F, with a 20 deg F diurnal swing.
(Relative humidity data are not available for the winter period).
Spring temperature and humidity: Roof sensor
The spring period temperature was overall warmer, averaging 50 deg F. Spring rainy days
can be seen when the humidity level peaks at 100%. Note that the graph shows the inverse
relationship between temperature and relative humidity.
Spring illuminance: Roof sensor
Illuminance data are available only for the spring period, and as stated previously, are
valid only for relative, not absolute light levels.
The next section will present data collected on a room by room basis.