Project Files: Episode 50 — Synchronized Hydronic Loop Saves Towson Court House HVAC
Retrofit provides comfort, efficiency, path to decarbonization
When it began “raining” inside the Towson Court House, a leaky roof was assumed to be the culprit. But for the Maryland Department of General Services, the state’s property managers, the truth turned out to be much stranger.
It turns out there was such negative air pressure in the building from the HVAC system that outside water was literally being sucked in through the perimeter walls and joints. Ceiling tiles were visibly billowing and warping, even though the roof itself was fine. With outside air constantly flowing into the building, it became impossible to maintain temperatures at comfortable levels. People in the building complained of dampness, humidity, and pockets of hot and cold air.
At first, DGS (the Department of General Services) took a traditional approach to fixes, focusing on individual pieces of equipment like chillers, pumps, and air handlers. The maintenance team replaced several decades-old air handling units.
That didn’t solve the comfort issues, so they called in Chesapeake Systems, a Maryland-based HVAC consultant and equipment distributor, to evaluate the building system. They soon discovered it wasn’t a few pieces of old and faulty equipment; the entire HVAC system was completely unbalanced — dampers blowing into empty ceiling spaces, vital equipment plated up, disconnected control switches, tarps hidden in crawl spaces to redirect water, and more.
Simply replacing the existing equipment wasn’t going to be enough to heal this sick building. So DGS made the decision to totally vacate the Towson Courthouse, temporarily relocating its operations offsite, and install new, holistic, state-of-the-art HVAC system that would achieve two goals: optimizing comfort and, as mandated by the state of Maryland, increasing energy efficiency by at least 15%.
The challenges DGS faced were solved by a concept Danfoss and its partners were developing called the Synchronized Hydronic Loop. The system included:
- Three WaterFurnace 80-ton modular chillers, each with two Danfoss high-efficiency scroll compressors
- Fifty-two Danfoss pressure-independent control valves
- Four Danfoss HVAC variable frequency drives, installed on fan motors
- Six Armstrong Design Envelope Pumps with factory-mounted Danfoss VFDs
The variable-speed technology on the chillers, pumps, and fan motors act in concert, automatically speeding up or slowing down to adapt to the comfort needs of the building while optimizing efficiency.
The WaterFurnace modular chillers’ heat recovery capabilities brought two other benefits: simultaneous heating and cooling, with the ability to recover heat off the compressors producing hot water with up to a combined efficiency of 8 COP, and carbon reduction and electrification. While the chiller is producing chilled water, the system has the ability to recover as little or as much heat needed to meet the building’s comfort needs. This allows for the building to reduce natural gas consumption and carbon emissions by only running boilers during peak heating months.
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After the upgrade, occupants noticed a difference immediately — especially the district judge, who said the building was more comfortable than she had ever experienced or expected.
In its first six months post-upgrade, the Towson District Courthouse saw an average total monthly energy savings of 23%, equating to more than $2,000 in monthly utility bill savings. The new heat recovery capabilities meant the building used 59% less natural gas in October and November than it did those months in years prior. Due to the decrease in natural gas usage, total energy use was reduced by a staggering 55% in November 2021, the first month with significant heating needs. That data is evidence of heat recovery’s potential to substantially decarbonize and reduce overall emissions, even if a building does not convert to 100% electric operations.
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