Vacuum Insulated Panels
Findings #11, March 2014
VIPs Save Energy While Meeting the Demands of Real-World Construction
According to the U.S. Department of Energy, heating, ventilation, and air conditioning (HVAC) account for roughly 34%(1) of all the energy used in commercial buildings, a large percentage of which routinely escapes as heat through the building envelope. Vacuum Insulated Panels (VIP) are a promising technology that present new opportunities to mitigate those losses. Invented for use in major appliances, like refrigerators and stoves, VIPs use vacuum technology to achieve high R-values within a very slim profile. Until recently, the price and fragility of VIPs have undermined their investment value in building envelope applications, when compared with standard insulation panels. With more manufacturers entering the market, however, unit costs have declined, and it is now possible to consider VIPs for roofing applications, particularly for retrofits where space limitations prohibit additional roof height. GSA’s Green Proving Ground (GPG) program recently assessed a VIP installation for material performance at the Post Office and Courthouse in Camden, New Jersey, and used digital modeling to estimate cost and energy savings across various building types and climate zones. Researchers found that VIPs were more durable than anticipated, and that R-50 insulation can offer favorable payback in one-story buildings in regions with extreme climates and high utility costs.
What We Did
EVALUATED FOR RUGGEDNESS, EFFICACY AND ENERGY SAVINGS
In November 2011, GSA retrofitted a leaky section of the roof at the U.S. Post Office and Courthouse in Camden, New Jersey to improve its insulating performance. Due to limitations imposed by building design, the additional roof height required by standard insulating roof panels would have necessitated expensive modification of flashing, brickwork, and windowsills. GSA therefore elected to install VIPs to achieve an R-50 insulating value, avoiding any increase in the thickness of the existing roof structure.
Because they are vacuum-sealed, VIPs lose R-value and rigidity if cut or punctured; installation requires both careful site preparation and meticulous measurement. Researchers surveyed the construction team for lessons learned, with particular attention to how the fragile VIPs withstood the rigors of construction. Researchers also inspected the completed installation with an infrared camera in search of thermal leaks that would signal damage. Finally the team digitally modeled three types of buildings common to the GSA inventory: small (single-story), medium, and large office buildings. The modeling sought to determine the impact of R-50 roofing insulation on overall cost and energy consumption, and compared electric and gas savings by both building size and climate zone.
What We Found
What We Concluded
VIPS ARE A VIABLE CHOICE WHEN R-50 IS REQUIRED AND SPACE LIMITATIONS PROHIBIT CONVENTIONAL INSULATION
VIPs are a viable roofing choice in structures where building constraints make it expensive to accommodate the thickness associated with traditional insulation materials, and where an R-value of 50 is required either to meet code or to save on energy costs in extreme climates. In the case of Camden’s post office and courthouse, VIPs were 53% less expensive than modifying the roof to accommodate thicker roofing materials. Simulations show that R-50 roofing panels can reduce a building’s electricity bill by up to 8% and natural gas bill by up to 10%, with best performance in single-story buildings..
CAREFUL PLANNING LEADS TO OPTIMAL RESULTS
- Since perforation of any kind causes a loss in rigidity and R-value, using VIPs requires meticulous planning and rigorous onsite precautions.
- A clean roof surface that has been cleared of all remnants of the prior roof system is critical.
- Since VIPs cannot be modified once they are fabricated, the roof area must be precisely measured and panels sized to fit by the manufacturer.
- Choosing a trusted vendor who is capable of careful planning is key.
- Because insulation offers diminishing savings as R-value climbs, the cost benefit of increasing the R-value of insulation must be carefully considered.
For more information, contact: Kevin Powell, Green Proving Ground Program Manager.
These Findings are based on the report, “Vacuum Insulated Panels in a Roofing Application Camden U.S. Post Office and Courthouse Camden, New Jersey,” which can be downloaded here .
Reference above to any specific commercial product, process or service does not constitute or imply its endorsement, recommendation or favoring by the United States Government or any agency thereof.