Gore Multi-Sports Complex

Gore Multi-sports Complex

Front view of Gore Multi-sports Complex during construction

Ice skating rink

Ice skating rink

Front view

Front view of Gore Multi-sports Complex

Swimming pool

Swimming pool

Techlink would like to thank Simon Taylor for his contribution to this case study.

Introduction

Local communities and schools are investing in new and upgraded sports facilities throughout New Zealand, for these communities both large and small, engineering energy efficient designs with cost-effective capital and operating costs are critical to their viability and success. The Gore Multi-sport Facility project is an example of how a smart design has made the project viable. Simon Taylor, Senior Mechanical Engineer at MWH outlines the problems faced and the solutions developed.

The Gore Multi-sports Complex incorporates an ice skating rink and an aquatic complex, comprising a 25m swimming pool, a leisure pool and hydrotherapy spa. Developed separately, the high energy and capital costs of these facilities would have made them prohibitively expensive for the community of Gore District. Combining the heat removal from the ice rink with the water and air heating for the pool, made this facility possible.

The process works using heat pump technology. Heat pump heating is a fairly common practise in aquatic centre design where alternative heating fuel cost is higher. Gore's unique feature is using the by-product, the cooling effect, of the heating system for the Aquatic Centre to provide cooling to the Ice Rink with practically no increase in energy consumption.

The total energy used by the facility is extremely low. The monthly electricity energy consumption for heating/cooling and power of both facilities is in the order of 140,000 kWh in winter, despite the extreme conditions in Gore. This compares well with heating and electricity usage of 170,000 to 250,000 kWh used by similar Aquatic Centres in the lower North Island, without the Ice Rink.

 

The Problem

Views of the outside

Views of the outside of the Complex

Entrance construction

Entrance construction

The project was for two organisations with a common interest: Gore District Council (GDC) and Ice Sports Southland (ISS). GDC had an existing swimming pool heated by a coal-fired boiler which is the cheapest option in this region for heat energy but is not environmentally positive. The facility was in a poor state of repair and in need of replacement. ISS, a private organisation, with a considerable membership, had an existing ice rink in a wool store building that was too small, very energy inefficient and they struggled to keep good ice in the uninsulated building. Both facilities were very old, expensive to run and far from ideal.

Steve Bunting, a member of staff at GDC had been overseas and seen an ice rink and pool connected together (Conceptual statement) but was unsure of the engineering behind such a facility. GDC and ISS identified that they would like to work together and obtain new facilities.

COP Brief development

Several important considerations were taken into account in the development of the sports facility.

Specific technical requirements included:

 

Solutions

Construction

Construction

Base of ice rink

Base of ice rink

Freezer unit

Freezer unit

Achieving simultaneous –9 and +45°C flow temperatures with an affordable 'off the shelf' chiller

Two independent control systems have been provided, one for the coolant temperature and one for the heating circuit temperature. The coolant temperature is controlled by the requirement of the ice temperature and is manually adjustable to suit the activities. The heating circuit is controlled by two sequential control loops. If the heating circuit temperature is too high, the heat rejection dry cooler will run. If the heating circuit temperature is too low, the heat pump coil at pool exhaust air will be used to draw more heat to the system.

Maximising use of coolant and stable operation of the cooling plant

A cascade coolant circulation system maximises the cooling effect of the coolant, and creates an overall coolant temperature difference of 4 to 5°C. This allows the total flow rate of the coolant to be reduced substantially by as much as 70%. The evaporator of a standard “off the shelf" chiller can now be used avoiding excessive pumping and cooling energy usage. As the chiller is operating sufficient temperature difference, no special coolant supply temperature control is necessary.

Making best use of low grade heat

A characteristic of heat pump heating systems is that the temperature of the heating media is relatively low, 40 to 45°C, comparing with 80°C commonly available with boiler heating. The use of lower heating circuit temperature will increase the efficiency of the heat pump system. With the low grade heat, the supply air temperature is limited to not more than 32 to 35°C depending on the heating medium temperature at the time. Although it is possible to design a heating coil to achieve a higher air temperature with the low grade heat, the much higher air resistance of the deep coil will significantly increase the fan power requirement. The challenge is to achieve the highest temperature air using the low grade heat, thus reducing the total air flow to meet the heating demand. High air flow rate will significantly increase the energy usage.

 

Design

Pool construction

Pool construction

concrete slabs

Pool construction – concrete slabs

Pipe work

Pipe work for tots pool features

Designing a control system to adjust the plant operation in accordance with both changing climate and facilities utilisation

At both the swimming pool and the ice rink, cooling and heating energy can be significantly reduced if the fresh supply air flow rates to the space are kept to the minimum. Variable speed control has been provided to the pool air system to ensure only minimum fresh air supply air flow to meet the heating and condensation control requirement. Recirculation control has been provided at the ice rink to limit the fresh air supply to meet the air quality control requirements.

Preventing freezing of system components due to low temperatures

The use of a single low temperature system for all cooling and heat pumping needs has the advantage of low capital and maintenance cost. This system however, requires anti freeze protection at cooling and heat pump coils, including all control and safety valves. The use of the cascade circulation system has also substantially reduced the risk of freezing.

Balancing the heating demands with the heat sources

The primary heat sources are the heat extracted from of the ice rink space cooling and ice bed cooling, plus the associated compressor heat. If heat from these primary sources is not sufficient to meet the demand, heat will be extracted from the exhaust air from the pool hall. A fine balance will ensure the chiller will operate at its optimum efficiency.

 

Development

Sand base for ice rink

Sand base for ice rink

pic1

pic2

Met tight project budget constraint

A sand-based ice rink as opposed to concrete was a cost saving measure. A sand-based ice rink requires a more involved ice building procedure and will have slightly higher thermal resistance to the heat transfer. Ice and space cooling in the Ice Rink was met by the otherwise wasted cooling effect of the heat pump heating system. The cascade coolant circulation system allows an affordable standard chiller to provide cooling to the ice bed.

Essentially the systems designed are both energy efficient and cost effective. They include:

Plant and equipment in this building is compact and space efficient. Installation of a waste water trap ensures that the facility places minimum load on the waste water system. This can be a problem in municipal systems where waste can deposit on the bottom of drainage systems during times of low flow and 'set', eventually producing a blockage. Special attention was given to preventing noise being a problem at the site boundary by specifying low speed fans and providing an acoustic barrier around the external condenser and air discharges. MWH worked closely with the architect to minimise the visual impact of the mechanical services.

 

Results

ice skating rink

Completed ice skating rink

Multi-sport Complex

Gore Multi-sport Complex entry

Completed swimming pool

COP Outcome development and evaluation

At the core of the facility is a 450kW water cooled chiller capable of supplying brine at –9ºC to keep the ice at the desired temperature. The heat generated from that process is then directed into the pool water and air heating plant in the form of water at approximately 45ºC.

A number of different options for the primary energy source for the overall facility were considered; the resulting heat pump concept not only saves energy costs but also from an environmental perspective is the lowest CO2 producing option. The concept design met the technical requirements and tight budgetary constraints.

The old ice rink cost $2,000 per month to run in energy costs now ISS pay $4,000 per month for the new facility, which has 5 times the ice area. The number of people attending public sessions at the rink has doubled and the membership of ISS has incrCompleted swimming pooleased. The facility has hosted the figure skating national, South Island championship competitions, and the Ice Hockey southern area regional championships.
The ISS can now offer curling, a popular sport throughout Otago and Southland.

This facility is a major change for recreation in Gore District. The new facility has created greater recreation options for the district and has made recreation much more accessible. It has provided a facility that puts the region on the sporting map and something that people of the district can be proud of.