FINDINGS

METHODOLOGY

The methodology adopted to test the team's primary hypothesis reflected both the somewhat limited array of equipment available to the team and the scale of the Great Hall of the National Building Museum. Time-series measurements of dry bulb air temperature were made at eight locations in the Great Hall in two series. The first series involved eight locations (two per floor) on the south side of the Hall. The second series involved eight mirror locations on the north side of the Hall. The eight measurements reflected conditions at roughly the quarter points of the Hall (toward the east and west) and on all four floors of the building. Six combination HOBO temperature and relative humidity sensors were used -- along with two HOBO temperature sensors borrowed from another team. The sensors were installed at roughly a four-foot height on the inside of the circulation elements that surround the Great Hall [specifically on the inside of the columns that form colonnades on the first and second floors, near the top of the balustrade on the third floor corridor, and near the top of the metal railing the defines the fourth floor circulation.] The illustrations below show the equipment types, method of installation, and locations of the various sensors.

HOBO temperature and
relative humidity sensor
HOBO external (XT)
temperature sensor
Installation [non-destructive] of
sensor on column in NBM

 

Plan of first floor of National Building Museum showing positions of sensors relative to the layout of the Great Hall. The south
sensors (bottom of plan) were installed first, they were then removed and relocated (as indicated) on the northern side of
the Hall. The four circles adjacent to the locator arrows are the major columns that frame the central part of the Hall.

 

Section through length of the National Building Museum showing locations of sensors on the four floors.

 

Contextual view of colonnades
that define temperature and
humidity measurement locations.
Bird's-eye view of circulation
elements on the four floors
of the NBM

DATA

Thermal conditions in the Great Hall of the National Building Museum will be reasonably constant in both the vertical and horizontal dimensions.

The HOBO data loggers used to collect temperature and humidity measurements were programmed to collect data once a minute. This interval was selected as a compromise between gathering too-much information and an attempt to detect patterns in a short time period. The sensors were installed on the south side of the Great Hall first (for approximately one hour) and then were relocated to the north side of the Hall (also for approximately one hour). This was believed to be a reasonable collection scheme for the limited time available. Six of the eight sensors recorded temperature and humidity; two of the eight recorded only temperature. All the HOBOs were launched in a central location and then taken to the Hall for installation. The size of the building required around 20 minutes for sensor installation. An hour of data was intended to be collected from each side (south and north) of the Great Hall. Because of the compressed time constraints, the dataloggers were run continuously during the afternoon measurements (approximately three hours total). The data clearly show these periods of transport, intended measurement, movement, and subsequent measurement.

The HOBO dataloggers were downloaded using Onset Computer's Boxcar software. The text file prepared by Boxcar was imported into the Quattro Pro spreadsheet program to permit manipulation of data sets, labels, and annotations. The data sets shown below have been selected to represent the measurements taken during Tool Day.

Dry bulb air temperature data collected on the south side of the Great Hall (east end) between 1:20 pm and 2:10 pm. The east-end data alone are shown to focus on the vertical temperature differences (if any) experienced in the Hall. The temperature scale is as indicated on the y-axis. The right hand side of the plot represents a period of stable temperature measurement. The higher temperatures to the left are an anomaly [believed to result from the fairly long time lag of the internal sensor on the temperature/humidity Hobo -- apparently tightly carried in someone's hand or pocket].

The maximum in-place temperature differential is around 4 degrees F. A possibility of stratification is indicated (although minor).

 

Dry bulb air temperature data collected on the north side of the Great Hall (east end) between 2:50 pm and 3:40 pm. The east-end data alone are shown to focus on the vertical temperature differences (if any) experienced in the Hall. The temperature scale is as indicated on the y-axis and is identical to the scale used in the graph above.

The maximum in-place temperature differential is around 4 degrees F. Some stratification is suggested.

 

Dry bulb air temperature data collected on the south and north sides of the Great Hall (east and west ends) between 1:20 pm and 3:40 pm. Only the data from floors 1 and 4 are shown to focus on the horizontal temperature differences (if any) experienced in the Hall. The temperature scale is as indicated on the y-axis and is identical to that in the graphs above. The left-hand box indicates a period of stable measurements on the south side of the Hall; the right-hand box similar measurements on the north side of the Hall. The excursions between the boxes and to the far left represent movement and handling of the sensors

The fourth floor temperatures appear stable over time and from west to east. The first floor temperature is less stable, and appears to decrease slightly in the afternoon (an oddity as the space is ventilated but not air-conditioned).

 

Relative humidity data collected on the south (at six locations) and north (at six locations) sides of the Great Hall between 1:20 pm and 3:40 pm. The "blips" between the boxes and to the far left represent handling and movement of the sensors [does the 80% RH represent a nervous hand?].

Relative humidity conditions are quite consistent across space and across time -- with less than a 10% differential seen while the sensors are in place.

SUB-HYPOTHESIS DATA

It would be interesting to assist the lighting team with their measurements.

Information from this effort is included in a report from another team.

It would be interesting to take measurements of surface temperatures throughout the Great Hall.

Measurements were taken throughout the afternoon using a remote sensing infrared thermometer. The data collected support the sense of a uniform temperature throughout the Great Hall developed from the HOBO measurements reported above. Perhaps the most interesting finding from this effort involved the supply air temperature to the Great Hall. Measurements of the surface temperature of the supply air diffusers throughout the Hall indicated that supply air to the space was not being cooled -- the HVAC system was acting as a mechanical ventilation system. Further consideration of these diffuser temperatures indicated a clear and consistent differential between supply air on the north side versus the south side in late afternoon (approximately a 2 degree F difference; measured with the same piece of equipment).

It would be interesting to see what the Great Hall looks like from the catwalks.

The saying that a picture is worth a thousand words applies here -- the following photo is the data addressing this hypothesis. The data collection methodology involved a digital camera -- and did NOT involve balloons or kite aerial photography. The investigator who collected this information shall remain anonymous (should his/her parents happen to see this WWW site). Note: from the roof of the Museum one can see the brick construction of the grand columns above the column capitals.

The view from the catwalk is superb.

It would be interesting to ask the building engineer about the operation of the building.

It is always interesting to ask building operators and occupants about their buildings. This visit was no different. The building engineer provided detailed information about the building HVAC systems that could not be easily obtained in any other manner. On Tool Day the Great Hall was conditioned solely with mechanically delivered outdoor air (an economizer cycle of operation). This, it was indicated, is typical practice at that time of the year. Even though ambient temperatures reached the mid-80s, the time lag of the materials and mixing of air provided by the space volume and air flow were able to maintain a comfortable environment -- even for the far-ranging Wanderers. The exhibit spaces are conditioned to museum-standard conditions using separate HVAC systems ingeniously housed in exterior wall cavity spaces.

HVAC unit for typical exhibit space.
The unit is located between an interior
wall of the exhibit space (to the right)
and the exterior wall of the building (to the left).

Team 2 Conclusions >


Tool Day Home | Team 2 Home | < Team 2 Background

This page was last updated on 8 May 2001.