Posted on March 16, 2023
Fort Wayne’s 7-story Pearl features a sustainable, energy-sipping temperate parking garage, event hall, and more
Planning for The Pearl, a new luxury apartment and mixed-use retail building along Main Street in Fort Wayne, started a few years ago. In initial planning meetings between Surack Enterprises, which owns and operates the building, and R.E. Dimond and Associates engineers, the building owners knew they needed an answer to several questions specifically related to the building’s heating and cooling systems:
- How do we ensure each apartment and business has their own thermostat and individual meters so people pay for their own energy?
- How can we heat and cool the building while reducing energy use and keeping client energy costs low and consistent?
- How can we maintain the highest efficiencies across the whole building?
- And in a unique twist: could we heat and ventilate the parking garage, and if so, how?
Engineers quickly identified a water source heat pump as the best at energy savings, stellar heat rejection and cooling capacity, and an efficient heat exchanger with a host of other benefits for the building.
Water source heat pumps on a central system move heat around the building more efficiently in summer and winter
“This is a central system, like in your car,” Dan Dimond, R.E. Dimond and Associates President and designer on the project explains. “When you’re in the sun and need AC, and the people next to you are in the shade, you need an efficient way to move air around inside.”
Like one side of a car, The Pearl’s large, glass windows let in lots of sun on its south wall. “On a 40º day, the north side of The Pearl may need heat and the units on the south side will need cooling.” By pumping water through a series of pipes on a closed building loop like veins in our bodies, the water source heat pumps can absorb heat from the south side and carry it to the north side where blowers push the tempered air where it’s needed.
“It’s really efficient,” says Dimond. “At least double and often three times or more efficient than a line of standalone heating and air units for each apartment.” The cooling load efficiency is significantly increased with evaporating cooling towers, too.
Traditional air-cooled condensing units on the roof or the ground are much less efficient than water-source heat pumps because the pumps will use a cooling tower to reject heat. “We can give these water source heat pumps much cooler water, like 85º when it’s 95º out.”
For comparison, a traditional air-cooled condensing unit might pull in 95º outdoor air, then cools it down with refrigerant before blowing air over it and out into a room. “It makes a big difference to use a cooler median temperature of water in the cooling season,” says Dimond. The refrigerant is also a hazardous material to work with, unlike water source heat pumps which have a completely self-contained refrigeration system that is less likely to leak.
It’s also more efficient in the winter. “In heating mode, we’re using a high-efficiency gas-fired condensing boiler to provide 60-70 degree water instead of an air-cooled heat pump trying to pull heat out of 10º air from the outside.” Similar to standard home furnace units, traditional heat pumps don’t work well below about 15-20º. In sub-freezing temperatures, auxiliary electric resistance heat systems activate to warm the air, dramatically increasing electric energy consumption.
Managing event center, restaurant, and temperature-controlled parking garage spaces
The Pearl features a large event center and space for several full-service restaurants. Because the water loop is so efficient at absorbing, rejecting, and moving heat the restaurant’s excess kitchen heat can be pumped upstairs — almost as if the restaurant were part of its own geothermal system heating the entire building.
“We’ve also got a motorized valve in each heat pump so if it’s not heating or cooling, it shuts the valve off.” This minimizes the flow of water in the building — almost like slowing down your heart rate when you’re sleeping — utilizing a variable frequency drive that takes less horsepower and energy usage.
“Perhaps the most unique thing about this system is The Pearl has a parking garage that’s tempered year-round,” says Dimond. The garage is heated with a water-to-water heat pump using the same water-source heat pump loop as the rest of the building. Few commercial buildings or office buildings could efficiently heat a parking garage.
Temperature-controlled parking garages pose challenges for ventilation, however, since the closed garage needs fresh air to reduce exhaust fumes. The air source system using carbon monoxide sensors to intelligently funnel fresh outside air in and cycle exhaust out. “The carbon monoxide sensors reduce airflow almost to nothing as if it’s shut off, like at night when there’s no need for as much heat in there,” says Dimond.
The Pearl is set to open in 2024, and is being built west of The Bradley and south of Perfection Bakery, bounded by Pearl Street, Webster Street, Main Street, and Maiden Lane. Up to $7 million will also be invested to improve the streets and public infrastructure around the site.
Water-to-water heat ventilation pumps and hydronic coils provide precise controls
Because The Pearl’s event center can generate excess heat when in full use, engineers installed a water-to-water heat pump to provide chilled water for that space. “And on the other side we’re using the system heat pump loop that serves the whole building.” “The Pearl has a dual temperature system, which are water-to-water heat pumps,” says Dimond.
Like the excess heat from the restaurant’s kitchen, the heat from a crowded event center can be pulled out of the crowded room and pumped upstairs to heat apartment units by passing water through other pumps — as if the building had two hearts capable of handing off responsibilities to each other.
“This water-to-water heat pump can provide hot water up to 140º to heat the parking garage and this big event center. And in the summer it provides cooling, too, which gives a lot more precise control for the event center with chilled water compared to a direct expansion [DX] system.”
Locating the air source heat pump and cooling tower flexibly for future growth
“The Pearl’s pipes don’t need to be insulated since you’re running water through them at 70º, essentially at room temperature — and that’s a huge benefit,” says Dimond. “The other benefit is it’s very flexible — as these restaurants come and go on the main level, we’ve got valves every so many feet and they can add pumps without having to shut down the system or mount big mechanical units on the roofs.”
Another advantage beyond excellent system performance is longevity. “You can never say ‘forever’, but the infrastructure like pipes inside the system is going to last basically forever,” says Dimond. “Lots of buildings in the 50s and 60s have these closed loop systems and they still work.”
He adds, “The head-end equipment, like boilers and the cooling towers are rated for 20 years. And the heat pumps here are inside, protected from weather, which allows them to last about 15 years, or slightly longer than weather-exposed systems.”
Even better, says Dimond, “Each unit’s water pumps and heaters are in 4×4′ closets in the corridors.” Meaning The Pearl’s maintenance teams never have to enter a tenant’s unit for repairs or inspections — they’re all accessible from exterior hallways.
Ready to install a water source heat pump in your building?
Indiana mixed-used retail and commercial building owners can benefit from high-efficiency water source heat pumps designed and placed by R.E. Dimond and Associates.
“Having a really efficient system is attractive to tenants — it’s a selling point because it’s lower monthly costs on utilities,” says Dimond. In addition, plans are underway to design solar power systems on The Pearl’s roof. These sustainable systems resonate with customers interested in sustainability and energy savings.
Water source heat pump installation costs vary depending on the size and geographic location of your building. A brief no-risk conversation will help us understand the best system design for your building.