DESIGN & CONSTRUCTION

Interview with LSPC Pool Designer, Jason Beirne, Winner of the 2017 Paul Kite Pool Star of the Year Award

Of the many design considerations, which would you say is the most challenging?

You may think that it's something deeply technical, but probably the biggest challenge is working within the confines of the space available for the plant room. Invariably people underestimate the space needed to build a highly efficient plantroom, from both a functional perspective, and also for the ongoing servicing of the plant. There is a natural tendency to think more about the glamorous part of the pool '- the pool shell '- but both elements should be considered in tandem.

We have certainly been involved in projects where the space allocated to the plant room is very tight and while we always develop a creative solution, for optimum functionality it's best to bring the design team in at the early planning stage so that we can advise on the best use of the all the available space. This way, the client gets the best possible design; a high-functioning and energy efficient plant room.

The amount of space required for the plant room will depend on the type of pool being built - the higher the turnover, the bigger the pool, the bigger the plant needed - every body of water (ie pool) needs to be considered on its own merits, there isn't a one-size fits all solution. And there are other influences that affect the plant room design, for example, the air handling unit. A client might have a small body of water but might have quite a large area for heating and ventilation, which means a larger air handling unit to accommodate in the plant room. All factors need to be taken into account.

The downside to squeezing plant into a smaller than optimal space is the impact on the efficiency of the pool '- for instance, chemical consumption is likely to increase, the plant itself may need to work harder because the pipework has to be plumbed into a smaller space and, because the pumps will need to work harder to compensate, the pool may need larger pumps which cost more and consume more energy. In an age when we are all trying to reduce carbon footprint, early consideration of the plant room space is essential to ensure that it doesn't consume more energy than necessary.

This plantroom is a great example of adequate space provision

What about the location of plant in relation to the pool?

As a rule of thumb, the closer the plant is to the pool the better its performance '- that's the ideal scenario as this eliminates the need to have pipes ‘stretching' around the building and water travelling further distances around the property than is necessary. However there are situations that force the plant room to be located a distance from the pool, even splitting the plant equipment over two areas (even on different floors). For example, a London town house might not have sufficient space in one area, in which case it may be that the filtration plant is located in one area and the air handling equipment in another area. A listed building or refurbishment projects are other example '- sometimes it's impossible to get the plant near the pool because of the existing structure. In these situations, we design a plant room that fits the accessible space by installing pipe and duct routes around the building to connect the plant to the pool.

At what point should we be planning for noise reduction?

Some clients prefer to site the plant room away from the pool as they worry about hearing noise from the equipment. However, advanced technology means it is far less of worry today. We provide noise levels as part of any planning permission required for the pool build and then we work closely with the architect and M&E consultants to integrate noise reduction technology into the plant room design and build. If we're incorporating items such as a counter current machine, we specify the modern quieter models.

What about access for servicing?

Early consideration of how the service engineer will easily get in and out of the plant room is a vital. Keeping the pool pristine involves transporting and storing chemicals for water treatment and the room may be equipped with ladders, pulleys and platforms to manage the process. The space for all this kit must be taken into account at the outset or the client could end up facing unnecessary adaptations further down the line.

When do we need to think about balance tanks?

A balance tank keeps pool water at a constant depth by fluctuating up and down and is required for semi level deck, overflow and infinity pools the bigger the pool the bigger the balance tank required. The balance tank can be integrated within the plumbing or built elsewhere, for example, in the garden '- think about its location within the overall design. A skimmer pool doesn't need a balance tank and consequently uses the least footprint in the plant room; it could be a good option for projects where plant room space is limited.

What are the drainage requirements?

Drainage must be considered from the filtration aspect and getting a drainage survey is the starting point. This will help to determine the requirements for drainage points for emptying the pool and to cater for backwashing if the filtration system chosen requires backwashing. We calculate how much water will be expelled from the pool and then size the drains accordingly so they can manage the water load and share this information with the architects. As part of the build process, we test that the pool is watertight by filling and draining the pool (and refilling again of course) and this is also a good test of the drainage system. We're often asked how often the client needs to drain the pool, but this is a rarity, perhaps once every 5-6 years for servicing, for example, to maintain the tiles.

What is the importance of a backwash storage tank?

A backwash storage tank is used to house chlorinated water for a given amount of time before it is treated and later expelled at a certain rate. This is usually required in conservation areas but often also applies to locations which have particular discharge regulations that must be adhered to for environmental reasons. If a project site does not allow water to be expelled at the desired rate because the drainage is insufficient, you will need to consider incorporating a backwash storage tank into the pool design.

What are the critical factors for heating and ventilation?

We work very closely with specialists, Heatstar and Calorex on the heating and ventilation requirements of pool halls. There is an excellent article on the subject by Heatstar in the hub, so that's the first place to start. The additional important point to note is that there are two ventilation requirements: first, ventilation of the plant room requires 4 to 5 air changes per hour, and the chemical store (chemicals for the water treatment system) must also have adequate ventilation, between 10-15 air changes per hour. We brief the M&E contractors on the ventilation requirements for the chemical store and they build the unit to meet the stated requirement.

What are the pool heath methods and requirements?

Pool heating for indoor pools is incorporated into our ventilation system. For outdoor pools, we consider supplying the plant room with a gas or oil boiler or we may recommend ground source heat pumps which are becoming popular because they are very energy efficient, though there is a higher upfront cost for the unit. Typically we consult with Heatstar, Calorex and Certikin to work out the calculations based on costings of different energy sources. This provides the adequate consultancy to make the decision on the best system for the type and size of pool being built. No doubt you will want these calculations when you, as the architect, are preparing the documentation for planning consent. Finally, if the pool is to tap into the house's main source of energy, the M&E consultants will be informed of the pool's requirements.

What are the electrical supply considerations?

This is straight forward '- the M&E consultants and the installation team will need calculations for everything that needs an electrical power supply '- air handling units, pumps, UV filters, lights etc. We provide all the calculations, whether that's 3-phase or single phase, and share the information on a timely basis, and they will advise when the supply is ready. Of course, we also specify the number of electrical points needed.

Would you recommend a building management indicator (BMI)?

It very much depends on the client's desire or need to control the pool. The BMI is a centralised hub which connects elements of the home, and the pool and spa can also be integrated to provide remote (eg via phone app) reporting on the performance of the pool or other elements such as heating, lighting, chemicals, UV, flow. The BMI will provide instant data to whoever is responsible for monitoring the pool system, giving them constant performance indicators. It's important to think about how much indication the client wants over each part of the pool/spa system so that the BMI can be designed accordingly at the outset. Some people just want to know what's going on with the pool, while others want indicators for all the equipment. If a problem is indicated, the pool manager/pool owner can contact our servicing team and an engineer will visit the site and investigate.

Summary

In my opinion, space and timing are the most important considerations for planning a pool. It's wise to discus all ideas and possibilities for the pool with the project team at the outset, and if things change on route ensure that everyone in the team is aware of the change. Many aspects of the pool design centre around space: this includes the size of the space for the pool, the ambience of the area for the pool and the space(s) allocated for the equipment. Not only must there be sufficient space to house all the equipment, the plant room must allow easy ingress and egress and be large enough for service engineers to move around with ease so that they can attend to the equipment quickly and effectively. Attention to space provision will result in a highly efficient pool and will avoid unnecessary expense for the pool owner.

The Paul Kite Pool Star of the Year Award recognises enthusiasm, willingness to learn, talent and promise in pool staff with less than ten years' experience in the industry.


Jamie Smith, Managing Director, at LSPC runs through the most frequently asked questions at the pool workshops with architects

How do you work with architects?

Our design team works in both 2D and 3D CAD systems which enable us to work seamlessly with the systems used by architects and building surveyors. We like to work as an integral part of the wider team involved in a project, ensuring that everyone is kept informed of progress and technical requirements.

Generally, we work with architects and designers at an early stage of the design; this is particularly important to ensure that the correct amount of space is allocated for the plant room. Plant room sizing is one of the biggest challenges we encounter '- when we are brought into a project at a later stage, invariably, we find that the designated space for the plant room is too small for the range of equipment needed to run the pool.

So, how big should the plant room be?

You will almost always need more room than you think!

Start by considering exactly what equipment needs to be well-housed in the plant room '- the equipment layout is important to achieve maximum performance and for easy access for future maintenance.

Plant rooms need to be sized to accommodate all the pool and spa mechanical equipment '- that comprises pumps, filters, a heating system, the water treatment plant (whether that's UV, ozone or chlorine pH control), ventilation system and all electrical equipment.

The ventilation unit and its accompanying ductwork will take up a lot of space. The ventilation unit for an indoor basement pool is 2 metres long by around 1.8 metres high by a metre deep off the wall.

You also need to consider the balance tank. It can be constructed outside the plant room, but generally, clients want it installed in the plant room; it's a large piece of kit that will take up about 5% capacity of the pool.

Taking all the above into account, generally, we advise that private pool clients allow between 8 and 12 square metres of floor space for the plant room.

Having said that, the plant room does not all have to be on one level. If a client is having a basement pool, there is no reason why some of the equipment cannot be located on a lower level.

What type of pools do you design?

Pool designs go anywhere from a traditional freeboard pool where the water sits between 150ml below the finished pool level of the pool surround, to semi-level deck systems, level deck systems, infinity and linear slot designs.

What are the main pool construction methods?

The main methods are Shuttered and Poured, PSS Block and Shotcrete.

Shuttered and Poured Method

With the Shuttered and Poured Method, a cavity is formed between two pieces of ply which are held together using various techniques and a steel reinforcement cage is built up in between the timbers. Once that work is completed and the penetrations have been put in for pipework and lights etc, concrete is poured to fill the cavity and vibrated-in to ensure there are no air pockets. On removal of the timber shutters, a bare concrete box will have been constructed.

Photo credit: Waters Edge

The PSS Block Method

The PSS Block Method is a permanent shuttered system, and the shutters are made of concrete slabs. They are formed in blocks and tied together with steel bars. As you build them up in a brickwork fashion, a cavity wall is built all the way up and more steel reinforcement is added during the process. Special starter blocks are needed at the bottom to create a cavity so that when the concrete is poured into the walls, the concrete runs out through the bottom and starts to form the floor to the profile needed. Once all the concrete has been poured, you have a monolithic concrete structure without any joins. With this method, it's essential that the concrete is poured in one day.

Photo credit: Permanent Shuttering Systems

Photo credit: Permanent Shuttering Systems

The Shotcrete Method

The Shotcrete Method is probably the most common method of building a swimming pool, where a back shutter, normally plywood, is erected. (On an indoor pool, you would use insulation material for the back shutter because all indoor pools need to be insulated.) Then a twin steel reinforcement cage is formed within the shutter. Once the shutter is completed, a special mix of concrete is pneumatically applied via a spray gun onto the back shutter and over the steel.

Photo credit: AQUA Magazine

Do you have any waterproofing tips?

Once the pool is constructed, it will need to be made watertight '- there are several options, for example, using a waterproof concrete admix, or an additive to the render or waterproof membrane or possibly all three on a particular pool!

It is possible for a pool to leak during the construction phase, so don't be concerned if this happens '- obviously this will be rectified during construction. However, it is very unusual for the pool structure itself to leak. If the structure does leak, in 90% of such cases the cause will be l inked to the penetration, where pipes go through the wall for example. Concrete does not adhere to plastic very well, so when building a pool structure, the sealing around plastic tubes must have something that bonds the waterproofing to plastic pipes.

Quite often, if we are building a concrete pool shell, instead of spraying the concrete all around the fitting, we leave a 'knockout', a hole in the concrete once it has been sprayed. The hole is then filled with the concrete and a hydrophilic strip wrapped around the part being fitted into the concrete. Once the fitting is in place, it is packed with waterproof concrete. Moisture in the concrete is absorbed into the hydrophilic strip which expands and creates a tight seal between the fitting and the concrete.

Alternatively, we may use Arbokol which is a two part epoxy that is mixed and packed between the fitting and the concrete or the render and then an elastic membrane is wrapped over the fitting, so that water cannot penetrate.

What are the circulation options?

There are three options: overflow circulation which applies to level deck, semi-level deck and linear deck slot pool types. Then there is the skimmer or freeboard pool '- the free board is the measurement difference between the water level and the floor level. And finally, infinity pools, where the water flows over one or more edges, giving the impression that there is no boundary to the water. Often these pools are designed so that the infinity edge appears to merge with a larger body of water, such as the Adriatic Sea, as you see in exotic holiday destination photos.

What key services are required for the pool's operation?

You will require electricity; single or three-phase, untreated (not softened) mains water, drainage for the plant room and filter backwashing/draining and also the primary heat supply for the air handling unit or heat exchanger.

Why do you need ventilation for an indoor pool?

It's essential to remove the evaporation that is produced by a pool. If pool evaporation is not managed, the moist air will condensate on cold surfaces and around the pool hall and cause damage. The moist air is sucked into the ventilation system and dehumidifier, pumping hot dry air back into the pool room. For more information on this, read the article by Heatstar.

I hope you find these FAQs helpful. If have a question that is not covered, please drop us an email at enquiries@londonswimmingpools.com and we'll add your question and an answer.

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