Hibernation of the aquatic centre during COVID-19 period

In these unprecedented times, our buildings and facilities need to adapt to a new way of working as we have done. In this article, we explore some ways aquatic centres can save energy and money during hibernation.

Over the last few weeks, several social distancing measures have been implemented to limit the spread of COVID-19 in different states and cities. Among those measures are the closure of indoor sport facilities and entertainment venues. Aquatic Centres are concerns and several centres across the country are now close to the public.

It is unknown how long those restrictions will be enforced for. However, it seems clear that it will last for more than 2 months (some predictions talking about 18 months). Aquatic Centres are typically the largest energy consumers of a Council’s portfolio and hibernating them during the COVID19 period could save a significant amount of energy and money for Councils.

Shutting down an aquatic centre is definitely possible, although some procedures must be clearly followed.

Here we propose three stages to slow down or shut down the aquatic centre:

1. Shutting down of the water heating,
2. Reprogramming of the HVAC system to slow down the pool hall air heating,
3. Shutting down water recirculation and drainage of the pool.

Shutting down of the water heating

This is the easiest and most immediate source of energy saving. All aquatic centres consume energy to maintain the pool water at a suitable temperature. The heat is supplied by one or several heating systems such as gas boilers, electric heat pumps, cogeneration system, solar thermal, or heat recovery systems. During this extended period of time where the pool will be unoccupied, maintaining the heating system active is not relevant.

For every heating systems, especially for gas boilers, heat pumps, and cogeneration systems, there are procedures provided in the user’s manual which explain how to hibernate such equipment. The purpose of a hibernation procedure (or extended shut down) is to ensure that the system remains inert and does not degrade during the shutdown period.

If necessary, get your contractor to attend the site and perform the procedure.

The BMCS should be maintained in operation during the whole period of COVID-19. If necessary, you can change the pool water setpoint to 0°C (in order to remove the need from the BMCS to activate heating and to avoid getting fault alarms).

The consequences of stopping the heating are:

• Heating water loops are stopped, which leads to energy savings from the operation of the pumps.
• Pool water will naturally cool down. Note that it could take several hours (up to one or two days) to heat up the pool water to its original set point when the centre will re-open. The timeframe requires to heat up the pool water depends on the water volume to heat and heating capacity available.
• Water heating systems in hibernation mode. No hazards related to the operations of the heating systems and savings on the maintenance costs.

Note that, when available, pool covers should be used during the whole period in order to protect the water from dust and reduce evaporation.

Reprogramming of the HVAC system (applies to indoor pools)

The next step of the shutting down of the aquatic centre is related to the HVAC system. This applies to indoor pools only. While the pool is unattended, heating and cooling of the pool hall air are not necessary. However, to protect the building from condensation, you must keep the relative humidity within an acceptable range and the air temperature above dew point!

Separately, you can slow down the fans used for the air circulation. It is important to keep the air flowing, but it should be limited to the strict minimum required. Reducing the air movement reduces evaporation from exposed pool water, which help to maintain the relative humidity within an acceptable range.

Get the pool operators or BMCS contractor to adapt the set points and controls of the BMCS:

• Reduce the air flow,
• Disable the air temperature set point,
• Disable the heating and cooling systems, unless when they are used to maintain the air within the acceptable RH range and air temperature above the dew point.

Shutting down water recirculation and drainage of the pool

Finally, the recirculation pumps could be stopped. However, this can have a significant impact on other assets and must be carefully planned. For instance, when recirculation pumps are stopped, chlorine used for disinfection of pool water will naturally degrade until none is left. At that point, microorganisms can strive especially with natural light. This can become a health hazard. If the circulation pumps are stopped, it would be recommended to drain the water out to reduce health hazards.

As a minimum, any superfluous filters should be isolated and put into a hibernation mode. Especially with UFF (Ultra Fine Filters), make sure you follow the protocols described by the manufacturer.

Note: if you slow down the pumps to save energy, make sure that you comply with the minimum flow rate required by the filtration system! Sand filters, particularly, do have a minimum flow rate. Below this value, water can create channels in which biofilm forms. These biofilms then accelerate the growth of micro-organisms.

Shutting down all unnecessary equipment

Finally, and this applies to any step above, shut down all non-essential items such as:

• Domestic hot water systems (for change rooms typically),
• Lighting, if on a timer,
• Any automatic features on a timer,
• Small A/C units for office rooms,
• Equipment from the gym.

Below is the typical energy breakdown of swimming pools

Now, consider your annual energy expenditure. Let’s assume $300k. Note that, as a rule of thumb:

• for an indoor pool, the energy consumption is fairly stable throughout the year, while
• for an outdoor pool, 2/3 of the energy is consumed during 1/3 of the year (winter).

With steps #1 and #2, the pool could save from $15k/month to $20k/month.

With step #3, the pool could save from $2.5k/month to $3.8/month.

All non-essential items could save from $2.5k/month to $6.3/month.

Note that this shutdown can be the opportunity to move forward with the implementation of equipment upgrade and energy efficiency improvements.

If you have any questions, the Northmore Gordon team will be happy to help.

Stay safe.