More than ten years ago technical staff was allocated responsibility to bring down costs of
operation of the ice rinks.
It quickly became clear that the maintenance of technical installations were done with
minimal documentation and what was handed over to the municipality did not contain
any useful information to evaluate performance. Protocols were generally of the type saying everything was OK. Moreover there were high energy costs and several problems that
required repeated maintenance visits without that cause of problems being identified,
so temporary fixes were done with the hope that the problem might not occur again.
Introduction of performance analysis.
The first step was to select one of the ice rinks and introduce ClimaCheck online (cloud based performance monitoring system) to establish a baseline and pinpoint what caused problems
and what opportunities for optimisation that could be documented.
The municipality’s energy coordinator then worked with contractors as well as experts to
correct several serious problems that increased energy consumption but also caused high
costs for reactive maintenance. As so often it was found that there were a combination of
different measures that resulted in energy savings of 40% and significantly reduced problems experienced in operation of plant.
Measures identified by performance monitoring and implemented was mainly what could be considered a major recommissioning based on real time information on performance including:
- Baseline of energy
Variable speed pumps were installed and flows tuned with compressors to allow stable operation with optimal flows.
- Resetting controls of heat recovery to recover as much as possible from condensers to minimise use of district heating and resistance heater that was used to heat water, dressing rooms and cafeteria as well as melting ice scraped from the rink.
- Optimising ventilation and dehumidification as these are essential to reduce load on the refrigeration system.
- Temperature of brine and ice thickness was optimised as thicker ice requires lower brine temperatures that decrease performance.
- Brine temperatures were optimised to activities as e.g. load during a tournament is significantly higher than during normal training.
- Expansion valves were adjusted.
- Dry cooler was tuned to balance heat recovery – not force high condensing more than beneficial but not dumping heat that could be used in the arena on the roof..
- Maintenance staff was trained to increase understanding of energy consumption and how they can affect efficiency and reliability.
A drastic energy saving was achieved where daily energy use decreased from 4 100 kWh to 2 500 kWh (39%) which allowed extending opening from 258 to 315 days (22%) the optimisation resulted in a reduced carbon footprint of 219 metric tons.
Online performance monitoring has after this been implemented on all six ice rinks in the municipality.
The project at “Älta ishall” have lowered their energy consumption with almost 40%. The more energy efficient system have also resulted in a much better business overall:
|1 385 816 kWh
||1 263 352 kWh
with 122 464
|Days open per
||Increased with 22%
||Increased with 40%
|Cost of energy
||Reduced with 30%
|Energy consumption per 24h
||Ca 4100 kWh
||Ca 2500 kWh (Dec)
||Reduced with 1600kWh (39.1%)
||546 000 kWh
||218,8 Metric ton