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Hotel Monville takes to the water for energy savings

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Hotel Monville
By Denise Deveau

When your goal is to create a ”new generation” hotel it’s not just about the décor and high-tech bells and whistles. For the recently opened Hotel Monville in Montreal, innovation was something that was considered from the ground up – including the HVAC systems for the 20-storey property.

”Heating and cooling was one of the first design considerations,” says Marc Saunier, asset manager for the property. ”Energy savings is extremely important in the hotel industry since it represents the third biggest expense after payroll and municipal taxes.”

Construction of the hotel started in the early winter of 2016.

Given this was a brand new hotel concept, Saunier, along with the engineering consulting firm BPA, had free rein to decide on how they could make the most of their energy savings. Rather than installing the usual dedicated heating and cooling system, they decided to take a less conventional route: leveraging the hotel’s domestic water system to provide the heating in winter and cooling in summer.

Saunier describes it as a completely self-contained design. It makes sense, given the fact that water usage by guests in hotels tends to be at specific times of the day.

”In the hotel business the water is mainly used for guests to take their showers in the a.m. and during certain times in the evening. Otherwise we just wait for them to come back. So we thought, let’s try to do something with the hot water in winter and do the same with the cold water in summer.”

”Typically you have a dedicated four-pipe system – two for the boiler and two for the chiller,” explains Dominique Frenette, BPA’s commercial market director. ”The difference with this is that we are connecting them to the domestic hot water system to reduce costs and cut down on the amount of pipes needed.”

Frenette’s history with the Hotel Monville owners goes back 17 years, when he designed and installed what was then a leading-edge energy efficient heating and cooling system at their boutique property Hotel Gault. This time around, he realized an entirely new approach would make for even greater energy efficiency.

While new to Montreal, leveraging the domestic water system for heating and cooling has recently seen some traction in Western Canada. There Frenette says he and his team did extensive research before putting pen to paper on this project.

Centralized Control

Each room is also connected to the central control system that manages all the mechanical equipment in the hotel. ”We can see every mechanical system and every control point from a central station,” says Joseph Rizzuto, an engineer with BPA. ”An operator can reach any one room to change temperature set points or whatever else they need to do.”

Saunier says the installation did increase the construction costs. ”However, the return on investment is very high. Compared to our older property Hotel Gault, we are using three times less energy for heating and cooling.”

Using an integrated piping system may be unique today, but it is being used more often in new design projects, Frenette adds. While Hotel Monville was a first for their company, they are using the concept in some upcoming apartment and condo projects to reduce energy costs.

”It’s a simple concept. Hotels and residential buildings have cold and hot domestic hot water lines, so why not use the same network rather than have a separate network for each? It makes perfect sense.”

The system

• 4 X Camus Dynaforce DRW2000 2 million BTUH boilers to heat the domestic hot water and the building.
• 2 X Carrier 100 ton air cooled scroll chillers.
• 1 – 150 ton Carrier water cooled screw chiller, with outside fluid cooler.
• 1 water recovery system on the screw chiller to recover rejected heat to preheat the domestic water – recovery possible 600,000 BTUH.
• 4 fresh air systems:
> 2 Spinnaker units in the mechanical room on the roof – one with heat wheel recovery at 11,500 CFM that serves half the rooms, plus one with plate exchanger recovery at 1,200 CFM that serves the common spaces on the 20th floor.
> 2 Spinnaker units in the mechanical room on the 3rd floor – one with plate exchanger recovery at 10,500 CFM that serves the other half of the rooms, and 1 with plate exchanger recovery at 2,000 CFM that serves the common spaces in the lobby and the first basement level.
• 2 X 1,200 gallon water storage tanks.
• 291 Williams fan coils that serve the common areas and guest rooms.
• 1 chilled glycol loop and 1 hot glycol loop for heating and cooling the common areas, meeting rooms and kitchen, as well as supply the fresh air units, and the snow melting system at the entrance of the building.
• 1 heat exchanger for heating the hot glycol loop and 1 heat exchanger for cooling down the cold domestic water loop.
• 1 central control system.

Scheduled Circulation

The fancoils installed in the guest rooms use chilled and hot domestic water. They contain low-lead materials and accessories so they can be used on domestic water systems, Frenette explains. They also have timers installed on the control valves to make sure that they are flushed with fresh water every 24 hours. The fancoils are installed in the ceiling of each guest room and the air is ducted to grilles under the large windows to ensure that no condensation forms on the windows.

Heating and cooling for public areas (lobby, meeting rooms, conference rooms, basement, kitchen, snow melt and fresh air systems) is run on a separate hot and cold glycol loops. Pumps circulate the hot and cold water throughout the day to ensure constant supply. ”Having the system recirculating all year long reduces the risk of bacterial growth,” Frenette says. Even though not necessary, a UV-treatment system was added to the domestic cold water to eliminate risk of legionella growth in the chilled domestic water loop.

A single system

In simple terms, the room heating system consists of four gas-fired boilers, two air cooled outdoor chillers and an interior water cooled chiller, which are directly connected to the hotel’s domestic hot and cold water lines. Hot water is supplied from two 1,200-gallon tanks.

Depending on the time of year, warm or cool air is directed to the rooms with fan coils.

”What we have created here is one single system that can provide water, as well as heat and cool the rooms all year long,” Saunier says.