Microclimate of ice rinks and swimming pools
Sergey Bruzgin, head of HVAC department in Metropolis, gave his expert opinion in Sport Build professional magazine with regard to design experience of sports venues /¹2 March, 2019/.
For each project a dedicated strategy of designing MEP services is developed based on the following factors:
• function of a sports venue (training or mixed-use, sports arena for international competitions etc.);
• geography of a sports venue;
• terms of connection to power supply systems;
• investment factors;
• history background (for reconstructed facilities).
Our company carried out projects for ice rinks and swimming pools of various functional purpose:
• Mixed-use hall of the Small ice arena VTB - Central stadium Dynamo named after Lev Yashin for 14,000 audience);
• Moskomsport covered skating rink at Michurinskiy prospect (capacity of tribunes - up to 300 audience);
• Mixed-use swimming pool Luzhniki;
• Sports and Recreation centre with a water park at Borisovskiye Prudy within the area of Tsaritsino natural complex, and other projects.
Microclimate of ice rinks
The main function of MEP services for the ice rinks is to maintain the temperature and humidity mode of the ice rink area, audience area and normal operation of structures.
One of the main problems in ice rink spaces is excessive air humidity above the ice rink surface with the temperature of the ice surface -5 °Ñ, which results in fogging. Specific attention should be also paid to the building envelope of the skating rink and adjacent rooms. Such structures affected by radiation cooling may assume the temperature values below the dewpoint temperature, and condensate may be formed on surfaces thereof. This is why the best finishing material for the ice rink roof is insulation material with a surface of aluminum foil with an absorption factor 0.1. Surface painting with light colours is also quite effective. For instance, plate steel painted white has an absorption factor 0.45.
There are two main ways to fight moist penetration:
• condensation process (air cooling to the condensation temperature);
• adsorptive process (the air passes through the material adsorbing moisture).
In our projects we use a combined system of moist removal for the warm period of year: an outside air is pre-cooled to the temperature of 10-12°C (usually a cooling medium 4/9°Ñ is used), this air further goes to the adsorption dehumidifier, where the air is finally dried to the required parameters of moisture content.
Like for the ice rinks, the main problem for swimming pools is excessive air humidity - a source of discomfort for visitors and the reason for premature wear of structures. Another problem is steaming of emissions from extract units servicing swimming pool areas.
For assimilation of excessive moist, the following main types of air handling units are used in swimming pools:
• ventilation plants with recirculation;
• energy efficient ventilation plants for swimming pools, with an integrated evaporator and a condensing unit, with a possibility of air drying and heating;
• energy efficient ventilation plants for swimming pools with a plate counter-current heat exchanger.
In our projects we use all the above mentioned types of units depending on the specific design conditions and the requirements of the Client.
Norms of air exchange
Outside air exchange norms per person both for ice rinks and swimming pools may be considered as almost identical.
Thus, using ice rink calculations as an example, according to norms, a sufficient outside air rate at ice rinks is 80 m3/hr of outside air per sportsman and 20 m3/hr per spectator. In big cities the CO2 concentration in the outside air is around 400-500 mg/m3. The maximum permissible CO2 concentration for a room is 1,250 mg/m3. A man of middle size emits around 15-23 l/hr of CO2 at rest. Calculating the minimum air flow rate per person, based on CO2 assimilation, we will get an outside air flow rate of 40 m3/hr instead of 20 m3/hr.
Another problem when fighting CO2 is its density of 1.98 kg/m3 as against the air density of 1.2 kg/m3. In other words, CO2 is heavier than the air, and in rooms with high CO2 concentration most of it will be at the room bottom area where people are located. Most often supply and extract ventilation units are located at the room top area, furthermore an ice rink area has greater height. Together these factors result in poor removal of CO2 from the room.
From experience our specialists made the following conclusions:
• the problem of high temperature and air humidity in the ice rink area is most likely related to the subsidence of air mass enriched with CO2 from tribunes to the ice field area. The air mass has increased temperature and increased moisture contents;
• the scheme of air supply and extract from top and upward (even if jet air distributors are used) needs to be checked using CFD-modelling in each specific case.
In order to optimize the design solutions, our specialists undertake CFD-modelling of the air mass thermodynamic condition in investigated rooms. It allows to estimate the correctness of adopted architectural and engineering solutions and make the necessary amendments at the early design stage, thus preventing mistakes, saving the Client's money, reducing the design period and time for adjustment of MEP systems.
Since modern designed facilities are provided with plenty of MEP systems, the only possible way to carry out the works with proper quality and within the shortest time period is to design with the help of BIM technologies.
Our company undertakes design works based on Revit software which helps to quickly get the data for CFD-modelling. At the construction phase a BIM model reduces the time and cost of installation works, and at the operation phase it replaces the design documentation archives.