Adjusting Internal Energy Loads in Glass Buildings

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Improving energy efficiency and worker comfort

From Toronto to Seattle, glass buildings are popping up throughout North America. They’re proven to maximize performance benefits and reduce heating and cooling costs when integrated with energy-efficient heating, ventilation and air conditioning (HVAC) systems.

And so many architects and engineers are starting to use natural light and heat in an effort to reduce costs and increase efficiency.

However, if you’ve ever worked in a glass building – or even in front of a glass window – you have likely experienced significant temperature fluctuations depending on the time of day and weather conditions. A brightly shining sun can cause interior temperatures to rise by nearly 40°F, which can make workers uncomfortable.

Energy in Glass Buildings
Energy in Glass Buildings

To compensate, occupants may open windows to compensate, resulting in direct energy loss. Without the ability to offset the temperature, occupants may relocate to more comfortable area or overheat, ultimately reducing productivity.

To combine the energy efficiency savings with worker comfort, more designers are incorporating low-temperature heating and cooling systems into building designs. This type of technology is ideally powered by renewable energy sources, such as geothermal or solar. It can also react quickly, which further translates into cost savings when evaluating productivity.

Energy in Glass Buildings
Energy in Glass Buildings


Wasted Heat, Wasted Money

While many buildings using glass facades generally are built with energy-savings in mind, low-temperature heating solutions provide an effective solution to limiting large temperature fluctuations because they respond quickly and provide almost instantaneous heating or cooling. Rather than requiring start up several hours before building occupants arrive in the morning, the system provides immediate output (within minutes), generating enough energy to heat the space in a short period of time.

Conversely, if there is a warmer day, the building is able to take advantage of the natural solar and internal loads. For example, studies have shown that sunlight that suddenly enters a building through double glazing can add more than 3400 BTU/hr per 11 square feet of glass to a room.

In order to respond quickly, the mass of the radiator has to be as low as possible. The lower the water content and weight of the heat emitter, the lower the inertia and the more controllable it becomes. Compared to in-floor radiant heating systems and radiant panels, radiators equipped with optimized heat exchange technology are better heat conductors and have a lower overall mass.

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Improving worker comfort has other benefits as well, including improving a company’s bottom line. Studies have shown that improved comfort can also impact occupant productivity. According to David Pogue, national director of sustainability at CB Richard Ellis, worker performance increases with temperatures up to 72°F and decreases with temperatures above 73 to 75°F. (Studies Link Green Design, Occupant Productivity)

Realizing these benefits, more low-temperature heating systems are typically being installed in both new build and retrofit applications. As building owners look to renovate older buildings with new technology or construct new buildings, old coal and oil-fired boiler systems are being phased out. Building owners are realizing energy savings of up to 30 to 40 percent above ASHRAE 90.1 and a return of investment of fewer than five years with low temperature systems.

Mini Canal at City West
Mini Canal at City West


Hydronic Cooling

Similar to the dynamic heating systems, hydronic cooling options also improve worker comfort by accommodating quick and efficient cooling. Because these systems can be equipped with individual climate control units, building occupants can set the unit to their preferred temperature rather than having a single thermostat control the temperature for every unit on a floor. This allows for more personalized control of temperature within a building occupant’s space.


Clima Canal
Clima Canal

Additional features of new energy-efficient hydronic cooling technology include:

  1. Extra Space. Forced air systems require extensive ductwork throughout the building, which means extra space. With new hydronic systems, ductwork is eliminated and extra ceiling space is freed – even up to one additional foot per floor. This gives architects and engineers the opportunity to add additional floors or penthouse suites in high-rise constructions compared to buildings using conventional force air systems. By choosing a hydronic heating and cooling solution, it is possible to generate additional and unanticipated revenue from extra suites within the same vertical footprint.
  2. Better indoor air quality. Building ductwork can be a magnet for bacteria and dust if not regularly cleaned and maintained. Hydronic heating systems help promote healthy, clean indoor air by eliminating opportunities for these materials to collect in a building’s ventilation system.
  3. Lower total cost of ownership. Largely constructed from renewable resources such as aluminum, low-H20 systems reduce the overall heating and cooling costs over the lifespan of the building.



Will it Work?

Typically, building owners and developers who are exploring glass facade options want to improve the environmental efficiency of the building. Yet, this can come at the expense of building occupants if HVAC systems do not react quickly to adapt to temperature fluctuations.

Low-temperature heating and cooling solutions can work in a number of applications, including retrofits and new build scenarios. For any system that operates using a low-temperature energy source such as a condensing boiler, solar, or geothermal application, low-temperature heating and high-temperature cooling systems are ideal together.

Due to its numerous benefits and return on investment, low-temperature heating is a system more building owners and designers are starting to explore. For a solution that delivers the “triple bottom line” of people, planet, and profit, it is a sustainable option that maximizes energy efficiency in glass buildings and makes sense for both today and tomorrow’s indoor climate needs — and for the health, comfort and morale of building occupants.

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  1. Typically, building owners and developers who are exploring glass facade options want to improve the environmental efficiency of the building. Yet, this can come at the expense of building occupants if HVAC systems do not react quickly to adapt to temperature fluctuations.


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