As the swimming pool located in Stalowa Wola was built in 1959 (with further upgrades), it shows significant heat losses through building envelope as well as through ventilation system. The U value of each envelope does not fulfill the requirements of the polish regulations, which also translates to higher energy costs. The energy source is a district heating system. It supplies the heating system as well as domestic hot water system.
In order to reduce energy consumption there will be carried out works concerning 4 areas:
– the envelope of the building,
– HVAC systems,
– installation of renewable energy sources,
Within the thermal modernization works, external walls will be insulated with the 18-20 cm thick styrofoam, flat roof will be insulated with 20-23 cm thick granulate wool. Old windows will be replaced with new ones with better thermal parameters (U = 0,9 W/(m2K)).
Very important role in modernization activities plays ventilation system. So far in the building were installed air handling units that were made for general purposes, without specific indications for hall indoor swimming pools. Accordingly, the materials used in the construction of units do not provide long-term and proper operation. Therefore there is the need to replace old air handling units with the new ones that allow the full treatment of air: heating, cooling and dehumidification. New units should have an exchanger with higher heat recovery efficiency. It can be achieved by installation of rotary heat exchanger (heat recovery efficiency equal to 90%) instead of the plate one (heat recovery efficiency equal to 65%).
There will be conducted modernization of heating system. Works will rely on exchange and adjustment of the system, installation of new radiators, installation of radiator thermostatic valves, so that will increase the efficiency of the system.
Significant energy savings can occur from the heat recovery from water rinse filter. The heat that occures in the technological water (rinse water filter), is lost to the sewage system. In order to prevent this, there are technical solutions which avoid heat losses. The system will be based on the heat recovery by use of a heat pump. The heat from technological water will be transfered to the water which supply pool. The technological water will flow from the overflow tanks at the tempreture about 27°C and it will be cooled to 10°C by the evaporator in the heat pump. The greywater will be used as a heat source for a heat pump with scroll compressor. The water which passes through the condenser can will heated up to 30°C and supply the pool at that temperature. The scheme of the system is shown in Figure 1. Annual production of heat from heat recovery form water rinse filter will be equal to 340 GJ.
Figure 1. Scheme of heat recovery system
An important element of the heat balance in terms of the complex is also a wastewater. The possibility of re-development of heat accumulated in wasted hot domestic water, water from sinks, showers should be taken into account.
They have a significant energy potential. Assuming 85 000 people entering the pool during the year and the consumption of 42 dm3/person we receive water consumption in the amount of 3570 m3/year. Annual production of heat can be equal to 168 GJ. This amount of heat discharged with wastewater will be possible to use as a heat source in the heat pump.
There will be installed the PV panels as well as solar panels. The maximum power of PV system will be equal to about 28 kWp. This amount of energy produced by PV system will help to cover the overall demand for electric energy.
The proposed installation of panels realizing photothermal energy conversion solar radiation, supports the process of heating the water in swimming pools and domestic hot water (hot tap water) in the building of the swimming pool. The solar installation should be designed as a system based on the circulation of charging and discharging of the buffer tank, whose task is to collect heat derived from solar panels. Installation of solar domestic hot water fully covers the demand in the months of June – July. The solar installation will cover 61.0% of energy for hot water.
The functioning of the solar system will reduce by 61% the energy consumption of the substation
used to heat the water. Assuming the price of heat 42,96 PLN/GJ, the energy cost savings will be 49 456 PLN/year. Assuming the cost of solar installation 1 312 160 PLN (2 000 PLN per 1 m2 aperture area), SPBT of the solar system is 26,53 years.
The modernization of lightning system includes the exchange of old luminaires to LED luminaires and implementation of lighting control system which uses data of daylight and the presence of the people in rooms. The system which uses this data will allow to reduce switching time of luminaires, which will have a direct impact on energy consumption. It will allow to reduce energy consumption by approx. 50% compared to the current state per year. In addition to greater savings, the lightning control system automates the process of switching on and off of luminaires what provide users with comfort in the building, and also raises the prestige of the whole sport facility.
It is planned that all energy improvements will reduce thermal and electric energy demand by 54%.
Table below shows the net costs of each energy improvement.
All works will start at the beginning of 2017. The ending of works is scheduled for the end of 2017.