Yale Curtain Wall

Stephen Kieran and James Timberlake
October 2005

Goal:
To determine the size and quantity of openings needed in the top and bottom angle stops necessary to induce adequate stack driven ventilation in the spandrel cavity between the outboard IGU and the inboard Kalwall panel. Adequate ventilation for this test is defined as maintaining a consistent cavity temperature of 120°F or less. The HVAC system design assumes an R-Value of 14 at the spandrel panels based upon design calculations; therefore a compromised R-value could fall below this level. The actual R-value of the spandrel curtainwall assembly is being tested and determined by Architectural Testing Incorporated.

History:
Thermal chamber testing was performed at Architectural Testing Incorporated (ATI) in York PA on November 16th, but did not provide conclusive data that would allow the design team to make an informed decision about the exact size and placement of the ventilating holes. This was due to the fact that ATI test simulates incident solar radiation using IR lamps which emit long wave radiation instead shortwave radiation in the solar spectrum. Consequently, the difference in long and short wave emissivities of the various components of the curtainwall assembly led to inaccurate results. Nonetheless, it was determined that temperature stratification of the air in the cavity does occur, and that consequent air circulation through perforations in the top and bottom stops is achieved and causes the temperature in the cavity to stabilize.

Testing Proposal:
We propose inserting temperature probes into the installed curtainwall at two primary locations on the building; at the fourth floor spandrel on the unshaded northern portion of the east façade, and at the fourth floor spandrel at the south façade. The design of the stops, which snap in and out fairly easily, should allow for the proper stops to be installed quickly once their final configuration is determined by this test. Two panels will be tested side by side in each location, one panel will have no holes in the stops, and the other will have holes in the stops as shown in the attached drawings. Probes will be placed in the cavity as shown in the attached drawings. The probes will be attached to battery powered data loggers and readings will be taken continuously until June 2007, which will encompass the spring shoulder season. In addition to internal curtainwall temperature probes, an interior station will monitor the ambient temperature and relative humidity of the building air volume adjacent to the spandrel panel, which will help determine if the assembly R-value compromised by ventilation holes.

Climatic data indicates that the periods of greatest solar and air temperature driven thermal stress will occur in May and late September/early October. A third set of monitoring equipment, measuring external temperature, humidity and solar radiation data will be placed on the roof of the building, which will provide baseline climatic data to compare against measured temperatures in the cavity. The data loggers will be monitored by either Isaiah King, a former employee of KTA, now currently a graduate student at the Yale School of Architecture or by KTA construction administration staff during their normal site visits.

HOBO Data Thermocouple Loggers
(first four left to right) 4-Channel Ambient Air Temp Logger (last one to the right)

(Left)Thermocouple Sensors for Nanogel Kalwall Surface
(Right) Ambient Air Temp Sensors

(Right) Ventilated Nanogel Kalwall Assembly
(Left) Non-Ventilated Assembly

Ambient Air Sensor Installed on
Inside Face of Low-E IGU

Thermocouple Sensors Installed on Nanogel Kalwall Panel

© 2007 KieranTimberlake Associates LLP
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