NextGen solar thermal curtainwall
11 June 2008 | Educational, Monitoring, Research
photo © Peter Aaron/Esto
Completed in 2006, the Yale University Sculpture Building is a 51,000 square foot studio space for the undergraduate and graduate Sculpture programs of the School of Art. The program for the building called for an exceptional quality of light, low energy usage and operable windows. A climate analysis performed on the site indicated a strong seasonal variation, with significant heating loads during the winter and cooling loads in the summer. This presented the opportunity to advance solar wall technology.
Section diagram, Yale University Sculpture Building
To provide maximum daylight and exceptional energy efficiency, KieranTimberlake worked with the curtainwall manufacturer Schuco and Kalwall Corporation to develop a wall system that incorporates solar shading, a triple glazed low-e vision panel, 8 foot high operable windows and a translucent double cavity spandrel panel. As a result, the entire skin of the building admits natural light and actively works to control the temperature in the building.
photo © Peter Aaron/Esto
The spandrel consists of a low-E IGU at the exterior, a three inch cavity, and a two and a half inch Kalwall panel filled with aerogel insulation. Both the IGU and the Kalwall are glazed directly into the thermally broken curtainwall mullion. Testing has suggested that the overall R value of the spandrel assembly is in excess of R 20 while maintaining 20% visible light transmittance. The cavity traps solar radiation, forming a warm air layer that further increases thermal performance when the sun is shining.
To expand upon the potential of the facade, interior temperature and humidity sensors, in conjunction with roof mounted humidity, temperature and solar radiation loggers have been placed within the spandrel chamber to determine if adequate stack driven ventilation occurs. Data procured to this point illustrates a significant capture of energy which could be used to drive ventilation or provide additional heat in the winter.
The NextGen Solar Thermal curtain wall builds upon this initial observation from the Yale Sculpture Building and explores a solar-thermal ventilation system driven by thermal convection currents. Within a controlled test chamber similar to the Yale Sculpture Building spandrel panel, we have introduced a top/bottom mullion with an integral operable damper and multiple ventilation apertures. The custom mullion/damper will allow us to iterate, test and validate ventilation strategies to optimize air flow (i.e. modulate the ventilation apertures) between the out-board IGU and in-board Aerogel panel. An anemometer will allow us to monitor the air movement through the mullions and air chamber. Sensors will also monitor the ambient air cavity temperature, surface temperature of the exterior face of Kalwall and incident solar energy.
Upon optimizing airflow, the dampers at the top and bottom of the chamber will be configured and tested for the following air venting strategies; winter heating, summer thermal buffering and natural ventilation. Winter heating will take interior air, heat it within the cavity and vent it back to the interior. Summer thermal buffering will take outside air into the cavity, heat it, and vent it back outside, minimizing thermal gains through the assembly. Natural ventilation for Fall/Spring seasons will draw air from inside, heat it and thermally drive it outside.
