Empire State Building, New York, NY
New York
Date: 2008-2009
Backerseal Part of 3-yr Payback Plan for $550 Million Dollar Energy Retrofit of Iconic Empire State Building
New York City, NY—Setting a new benchmark for large-scale, aggressive, energy retrofits of existing structures, the Empire State Building’s recent upgrade is saving up to 40% and $3.8 million annually in energy costs, has earned LEED Gold certification, and has proved the economic viability of whole-building energy efficiency retrofits in the pursuit of sustainability.
Backerseal by EMSEAL played a critical role in bridging the thermal breaks between the window frames and the wall elements of the 6,514 windows.
The project team, assisted by the Rocky Mountain Institute, evaluated 70 ECM’s (Energy Conservation Measures) by modeling them and chose only eight–among them the building windows.
Implemented together these eight measures are projected to result in a 38.4% decrease in energy consumption.
What does Backerseal do?
– Provides R-value at joints
– Provides watertight secondary seal
– Resists air pressure differentials
– Remains in compression
– Provides acoustic dampening
– Contributes to LEED
The sheer number of windows means they are a huge percentage of the facade of the structure.
It became quickly apparent that the windows themselves as well as the thermal breaks between the window frames and the walls of the building had to be addressed.
“By changing the building envelope insulation both through the windows and against the walls themselves, it lowers both the heat and cold loads on the building,” commented Stephen Doig, PhD, Program Director, Rocky Mountain Institute.
The existing failed sealant was a traditional backer rod and polyurethane system that had aged, dried, stiffened and separated at the bondline as the result of adhesion in tension.
A survey of available depths and widths was taken at various building elements.
Manufactured in a custom depth to suit the shallow joint profile, the Backerseal was installed behind liquid-applied silicone.
Backerseal was supplied in a range of widths and replenished just in time as consumed during installation.
Backerseal self-expands after insertion into the joint and remains in compression.
Backerseal installed between window-frame and stainless steel facade adornments. Supplied precompressed to less than joint size.
Backerseal coated with silicone liquid sealant to form hybrid seal system featuring improved R-value, waterproofing redundancy, and an ability to resist air-pressure differentials.
Working from swing stages, the window sealing was progressed on multiple elevations simultaneously and tracked on wall-mounted facade elevation plans in the job office.
Swing stages look tiny against the massive facade of the Empire State Building as crews work to reseal the 6,514 window perimeters using EMSEAL’s Backerseal behind silicone liquid sealant.
Using integrated design and whole systems thinking the cascading benefit effects of energy conservation measures becomes apparent. Looked at in isolation, upgrading and sealing of the windows would have yielded some savings but would have a 20 year payback.
Looked at in respect to the effect that upgrading and properly sealing the windows would have on the reduction of load on the mechanical (heating and cooling) systems, the results are altogether different.
“The way we as engineers like to look at it is what we call interactive effects. What we think about is, well, the windows will do some good, they’ll save some energy, but more importantly, they’ll make our systems smaller. Our heating system is smaller, our cooling system is smaller, that optimization is much different than just ‘what’s the energy savings from a better window?,” remarked, Peter Rumsey, P.E., Managing Director, Rumsey Engineers (now Integral Group).
In fact the building owner had expected that they would have to add heating and cooling capacity. Instead they ended up with excess capacity from the existing systems because of reducing and managing the heat load better.
“There’s massive innovation here, by looking at an integrated approach,” commented Malkin Holdings President, Tony Malkin.
Energy savings and capital cost savings looked at in combination yield a far greater return than looking just at the energy savings from projects in isolation.
A YouTube video of the project from the Rocky Mountain Institute can be seen by clicking here.