Energy Efficient Buildings | Refrigeration

Demonstration Projects

Video of the Val-des-Monts Arena Project

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1. Introduction

Narrator:

The sharp sound of steel blades crisply carving the frozen hardness of a pond, river or outdoor rink is as traditional in Quebec as are the legends that skated here with names like Richard, Lafleur, Chouinard, and Brasseur.

In Val-des-Monts, Quebec, it's time to build a new artificial ice-skating arena. It's time to rely on technology that produces a longer skating season, and reduces maintenance costs. It's time to unlock the sun's energy, free for the taking in the earth beneath the town!

Earth Energy In Our Community
A Ground Source Heat System for Val-des-Monts

Energy costs have never been higher and greenhouse gases pose a real and serious threat to our planet. Scientists and engineers, searching for a realistic solution, have concluded that the answer has always been right under their noses... and under their feet... in the form of Earth Energy.

The earth is a repository, which absorbs 47% of the Sun's energy, a total 500 times more than the annual energy requirements of all of humanity.

This "heat pump system" exploits the earth as a source of energy, an energy "well" that actually stockpiles energy. It's not new thinking. A Swiss patent was issued for the technology as long ago as 1912.

The infamous energy crisis of the seventies accelerated the idea resulting in some market success within the residential sector using groundwater type systems or more widespread still, ambient air.

The eighties brought about improvements in heat pump efficiencies and operating ranges. The introduction of better materials for ground loops assisted ground-coupled heat pumps to gain market success.

In North America more than 40,000 heat pump units are now sold annually. The system is particularly advantageous in Canada, where seasonal variations in climate result in a wide range of temperatures. Heat pumps contribute significantly as a renewable and sustainable energy source with low greenhouse gas emissions.

At a depth of 3 or more metres, the ground temperature remains constant year round, about equal to the average annual air temperature above. In the Val-des-Monts region this is about 5 or 6 degrees Celsius. Once installed in an environment where the temperature is constant, the earth energy heat pumps perform consistently. According to the Canadian average, they contribute to a decrease in greenhouse gas emissions of 40% compared to an air-to-air heat pump and 70% when compared to electrical base board heating. The coefficient of performance is a little better than 3, meaning that for 1 kilowatt of energy consumption, 3 kilowatt-hours of heat can be produced by heat pump action.

This means that they can be exploited in a number of ways in the creation of comfortable residential, commercial and recreational indoor environments. This includes those with conflicting needs like ice-skating arenas where the need for user comfort is coupled with a necessity to maintain one or more large sheets of ice.

In a mere three years the difference in cost between the ground source heat system installation and a conventional system will be recovered. An economical reduction in management, maintenance and energy costs makes it possible to offer services at a better price. In some cases it could make the difference between having or not having a skating rink.

Since energy costs represent one-third of total operating costs, this is good news for the president of the Val-des-Monts Recreation Association, Marc Louis-Seize.

2. Declaration from the President of l'Association récréative de Val-des-Monts

Marc Louis-Seize:

The cost of marketing an arena, is based principally on operating cost, in particular the heating and refrigeration. In order to serve the community, we have to keep the operating and maintenance costs down, especially heating and refrigeration. This permits us to minimize rental fees and ensures its optimal use.

Narrator:

The Mayor of Val-des-Monts also recognized the value of delivering a more comfortable and user friendly facility to taxpayers.

3. Declaration from the Mayor of Val-des-Monts

Marc Carrière:

This project is important for a major municipality like ours, in which 45% of our population are under 25 years of age. Our total population of 8500 doubles in the summer and we've been lacking in infrastructure for our young people. Obviously an arena of this scale will fulfill what were urgent and glaring needs for our youth.
 
I think it's vitally important for Val-des-Monts, where for years we've had an important environmental vision and where there are 125 lakes within the municipality which we would like to keep clean. I think that has to play a role and is a priority for us. That's why we're collaborating with the various participants in this important step."

Narrator:

To achieve the reduction of greenhouse gases a number of technologies could be used. Marius Lavoie is one of the engineers responsible for promoting new technology from the CANMET Energy Diversification Research Laboratory of Natural Resources Canada.

4. Declaration from NRCan's Engineer

Marius R. Lavoie:

A market survey indicated that, from an energy standpoint, there was much to gain from the establishment of new technologies in an arena. The preference was to seek a new arena in the planning stages rather than the restoration of an existing arena. While looking for a new site we met spokespersons from Val-des-Monts who were planning to build an arena and so we discussed the possibility of a partnership to establish new technologies.

At Val-des-Monts our objective was to thoroughly integrate techniques for the thermal storage of heat and cold. In order to maintain the ice surface of the rink at a constant temperature in spite of load fluctuations from heavy use , ambient temperature, lighting and other concentrated demands. To meet this need, we examined the possibility to thermally store heat and cold.

An arena produces both cold and heat. The cold is necessary for the skating rink and heat for other uses like heating the principal enclosure. When cold is produced, the heat pumps extract the heat from the ice and dissipate it either as energy for heating water or for heating the building. Unfortunately, the accumulation of heat does not always occur simultaneously with the needs for heating.

What we wanted to do was to thoroughly integrate geothermic technology within the building. Radiant heat from the floors warms areas at a much lower temperature. We also use the ground-based heat exchanger as a source, and storage buffer for energy. The cold from the snow pit cools the cooling agent before it passes to the evaporator.

We also wanted to exploit the benefits of the regional climatic conditions to the maximum so we drew upon the capacity of the ground as source of thermal wells where we can draw upon stored heat or where we can save heat when we have excess... The cold from the snow pit is recovered to assist the cooling agent in the evaporator. We can also use the cold of our Canadian winters with the use of a fluid cooler located outside.

The hermetically sealed heat pumps have been pre-machined in factory with a minimum of cooling agent so as to minimize the impact in the event of any leaks. Today, its not necessary to use refrigeration technicians to install this kind of heat pumps, plumbers are capable of installing systems such as one has here Val-des-Monts.

5. Declaration from the project's Architect

Leon Mercier:

After having designed the building to recover the most energy possible, there was the problem of coordinating the integration of the architectural, mechanical and electrical plans. It was difficult. It's especially important to have good coordination between the various professionals.

6. Declaration from the project’s Engineer

Pierre Meilleur:

The biggest engineering challenge in this project was to incorporate the existent technology. Now we worked with those who would worked on this type of project although not in Quebec. The biggest challenge was not apply known engineering principles to new application.

Narrator:

Reduction or elimination of greenhouse gases is always a prime consideration. This is particularly crucial in the face of potential damages caused by synthetic refrigerants. Hand in hand with the reality of budget constraints thorough research and astute decision making must prevail.

7. Declaration from the Head of Sales, Hydro-Quebec

Nancy Guenette:

Hydro-Quebec recognizes that ground based heat systems are highly competitive compared to the other energy sources which could be used. Of the many proposals for ground based heat systems, which have been proposed to our clients, this is the first for an arena in Quebec. It is much more efficient than other sources of energy, and when we monitor the operating costs, we regularly see them as being comparatively lower than what we find in traditional electrical systems.

8. Economic Factors

In a feasibility study engineers estimated that to integrate the Heating, Ventilation and Air Conditioning and Refrigeration system, or HVAC-R electromechanical systems with a ground source heat system would produce an additional cost of 25% over the cost of a conventional system. However, due to the operational cost savings from the groud heat source system, the additional initial capital investment of 30% would be amortized in less than 36 months of use. And, of course, the objective to limit greenhouse gas emissions would be supported.

Based on a 20 year life cycle analysis and compared to the lower initial cost but higher operating and maintenance costs of a conventional HVAC-R system, an HVAC-R system integrated with a ground source heat system was a more economical choice.

Electricity expenses are much lower with a ground source heat system. Annually, the electricity bill for overall consumption is much more palatable when it is 60% less than the bill for a conventional system, in a standard arena.

The operating costs of a conventional system are more than 100% higher than the ground source heat system. Dollars are freed up which can now be applied to other activities.

9. What is a Heat Pum?
 

It can contribute to the reduction of greenhouse gas emissions, and quickly pays for itself with reduced maintenance and operating costs, but how does a ground source heat pump system work?

The most common heat pump in Canada is the air-source heat pump that extracts heat from outdoor air and reproduces it indoors. A refrigerant propelled through a continuous cycle transforms from liquid to vapour to heated gas and then back to a liquid again. To cool the home in summer the process is reversed.

Refrigerators and air conditioners are both examples of heat pumps operating primarily in the cooling mode. A refrigerator is essentially an insulated box with a heat pump system connected to it. The evaporator coil is located inside the box, usually in the freezer compartment. Heat is absorbed from this location and transferred outside, usually behind the unit where the condenser coil is located. Similarly, an air conditioner transfers heat from inside a house to the outdoors. The heat pump cycle is fully reversible, and heat pumps can provide year-round climate control, heating in winter and cooling and dehumidifying in summer.

A ground source heat system is especially designed to refrigerate and heat simultaneously at effectiveness levels much higher than conventional separate heating and refrigeration devices. The principal applies perfectly to arenas.

An arena refrigeration system is like a large air-conditioner that runs in reverse during the cold season, providing heat to a building.

10. Characteristics of Val-des-Monts'HVAC System

Val-des-Monts
Setting the Standard for Economy and the Environment!

The ground source heat system design in Val-des-Monts is better still. Special modular units are used to create cold while others are used to generate heat. When the need for refrigeration and heating aren't even, surpluses of either heat or cold accumulate in storage buffers for later use.

The refrigeration system is composed of effective low-temperature heat pumps and of various pre-assembled factory components. Compact in size, the cooling agent is sealed hermetically. The modular concept integrates easily into the various heating, air-conditioning and refrigeration equipment within the building to produce either cold or heat. It's not even necessary to retain specially trained personnel, such as licensed refrigeration technicians, to install and operate the system as would be needed for ammonia-based refrigeration systems.

The increased efficiency of the ground source heat pump system contributes to a healthier breathing environment and delivers a reliable source of heat, general-purpose hot water and very hot water for resurfacing.

And unlike conventional systems a ground source heat system can maintain efficient results even during extreme summer heat and the coldest days of winter because of the transfer of energy contained in the ground, where the temperature remains consistent. Val-des-Monts even further exploits the cold of our rigorous Canadian winters.

Several ground source heat systems can provide hot water while making cold, which further increases their effectiveness. In Val-des-Monts, the ground source heat technology is deeply integrated with the Hvac technologies of the building, including heating, air-conditioning and general-purpose hot water.

The ice surface machine requires water to be heated up to 85°C. To achieve this, an additional heat pump comes on line to bring the water temperature to 60° before a standard heater is needed to lift the temperature to the final desired temperature setting.

Like a household refrigerator, a heat pump always has a cold side and a warm side. Every possible effort is made to use the two sides simultaneously to maximize the total performance of the system. In a standard arena, generally it is the cold producing side that dominates. As such, the refrigeration system extracts three times the heat necessary to satisfy the heating needs. In an attempt to save some of this heat so as to reduce the need for heat from other sources, heat is stored in hot water tanks and also directly in the ground.

In Val-des-Monts the ground source heat system is maximized as the heat extracted from the ice rink:

  • Is used to heat the viewing stands, dressing rooms and other parts of the arena facility
  • Is used to heat the hot water tanks
  • Is used to heat the nearby Community center
  • Is stored in the ground based thermal storage buffers
  • And is directed toward the condenser when all the other needs are satisfied

Or, as often happens, the excess heat generated from making ice is stored for later use.

Demands on the working installed capacity of the refrigeration system are decreased by a further 50% with the use of an innovative concept in which cold is stored under the principal flagstone. One of the great advantages of storing cold in this way is the ability to operate the refrigeration system on an as-needs basis, thereby lowering the demand for power. Moreover, in the event of a power outage, the inertial of thermal cold storage will preserve the ice surface for several days.

To achieve maximum effectiveness ground source heat technology must be deeply integrated into the other Hvac technology in the building beginning with orientation of the building itself. In Val-des-Monts the building was situated so the sun could heat the southern side. To diminish greenhouse gases the building was designed according to the new Model National Energy Code for Buildings (MNECB). To qualify for funding through CBIP the design had to be at least 25% more energy-efficient than a reference design that just meets the MNECB requirements. The heat recovery system in Val-des-Monts including all other conservation measures produces an eye-opening efficiency that exceeds the energy code by more than 60%.

Since the HVAC refrigeration system is smaller than in a standard arena, the liquid coolant circulating pumps are also smaller. Better still, instead of using 15 to 30 HP circulating pumps, the thermal storage refrigeration system requires 2 to 6 HP pumps. The lengths of each section of piping in the flagstone of the skating rink, used as an exchanger, are optimized at 1000 feet rather than the standard 400 feet. This eliminates two thirds of the connections as well as the pipe collection pit traditionally located in the end of a standard rink. By eliminating large circulating pumps the energy savings can be enormous.

The coefficient of performance or COP is used to measure the efficiency of heat pumps. The COP at Val-des-Monts has been improved in a number of ways.

The COP for cooling is calculated using an equation that divides the amount of heat produced by the heat pump by the quantity of electricity needed to achieve a given temperature. The difference between the start temperature and the desired temperature.

Is called the thermal lift. Simply, the smaller the thermal lift the better the COP of the heat pump. A similar equation is used to calculate the COP for heating. So, to minimize thermal lift at Val-des-Monts the HVAC system and the arena itself have been carefully designed.

For example, heating the building at a lower temperature while achieving the same degree of comfort will improve the COP. For this reason radiant heating from the floor has been installed. This permits the liquid coolant to be maintained at 21oC lower than the 42oC needed for heaters in standard arenas.

To improve the thermal lift the snow gathered in an ice resurfacing is recovered and dumped into a specially outfitted pit that serves a dual purpose. While melting, it contributes to an increase in the output of the refrigeration system, which uses the cold to dissipate the heat of the cooling agent before it enters the evaporator. During cold weather, the fluid cooler from outside will be used similarly. By decreasing the thermal lift in this way, the workload of the refrigeration system is decreased and its performance also rises. In this way the cold Canadian climate in Val-des-Monts is put to work toward the energy efficiency of the arena.

Centralized controls make it possible to optimize the operation of the system. In an idle period the ice temperature will rise while the ambient temperature drops. The distribution and the levels of lighting can be managed according to established schedules. All of this contributes to a lower electricity bill.

The low emissivity ceiling decreases the refrigeration load about 6% while improving ice quality. The ceiling improves acoustics and lighting while preventing condensation from occurring. The wall colour was also specifically chosen to better reflect light. Electrical load requirements have been reduced from 25 kW for a standard arena to a mere 10.5 kW. Decreasing the power of the lights decreases the radiant load on the ice. Four levels of lighting intensity makes it possible to adjust for any specific activity such as hockey, figure skating, and free skating or for maintenance. These energy measures reduce the consumption of lighting energy by a factor of 5 compared with arenas that have only one lighting level, and savings of at least 75% over a standard arena.

To improve ice quality, and to protect the building shell while decreasing the refrigeration load, the air in the principal enclosure is dehumidified by other heat pumps integrated into the ground source heat system.

FREON(R22) to be eliminated by the year 2020
Standard arena – 750 KG of Freon
Val-des-Monts – 35 KG of permissible R404

The Montreal Protocol envisions the complete elimination of synthetic refrigerant by the year 2020. A standard arena uses more than 750 kg of synthetic refrigerant. In Val-des-Monts the objective is not only to diminish consumption and to reduce greenhouse gases, but also to exceed the basic requirements of law with the integration of more profound safety measures. Unlike standard arenas where CFC refrigerant is used, the compact and hermetically sealed heat pumps of the Val-des-Monts refrigeration system use only from 30 to 40 kg of the permissible cooling agent R404a which is non-threatening to the ozone layer. Were leaks to actually occur, the quantity would be minimal and the consequence would be negligible. A secondary refrigerant called Glycol is used to transfer heat or cold from the heat pump to the other systems. If it were to leak it's less threatening to the environment.

Design, Installation and Planning

The installation of a ground source heat system requires significant exterior civil works including a geo-technical evaluation and a careful definition of existing services. Detailed plans and specs referencing CSA 447 may be required to be submitted, to the local authority. Proper design, sizing, and installation of a ground exchanger is critical to the performance of the system. In Val-des-Monts a horizontal loop design was the right choice for a number of reasons, beginning with the accommodating geology, and high water level of the building site which would contribute to a better performance of the system. The horizontal installation also eliminated the need for additional contractors and expensive drilling technology.

Life Expectancy, Guarantees and Maintenance

Liquid-to-Liquid heat pumps generally have a life expectancy of 20 years, while the ground loop should last at least 30 years.

Earth Energy System maintenance costs are far below that of conventional systems however the changing of air filters, motor lubrication, replacement of fan belts are still required. In addition anti-freeze concentration and inhibitors must be checked and heat exchangers, grilles or registers and ducts must be kept clean. The compact units of the refrigeration system installed in Val-des-Monts don't require licensed refrigeration technicians to attend to rigorous maintenance schedules for autumn start-up or spring shutdown operations.

Measuring System Performance

The Val-des-Monts project is complete. The results are most impressive. Nancy Guenette of Hydro Quebec confirms the performance of the EES.

11. Summary

Narrator:

For facilities that house such activities as ice-skating or curling the benefits of a refrigeration system twinned with a ground source heat system, deeply integrated into the HVAC systems of the building are undeniable.

  • Savings of forty-thousand dollars in operating and maintenance costs with a payback period reducing the additional costs in less than three years
  • Local mechanical contractors provide service rather than refrigeration specialists at startup times
  • When retrofitting no electrical service upgrade is needed
  • Simple maintenance without extensive training for arena operators
  • Eliminates annual fall start-up and spring shutdown costs of a conventional ammonia or synthetic refrigerant ice plant
  • Single billing system for ice making and space heating
  • Harvests the renewable energy accumulated in the ground

The residents of Val-des-Monts, Quebec, as in other Canadian communities, can now take pride in their energy efficient and renewable energy venture that ensures a comfortable environment will be enjoyed by all for many years to come.