Design of Efficient Renewable Energy Systems
This page of the website is all about heating costs. However this is not the only cost associated with pool maintenance as chemicals also need to be purchased - the cost of these can also be minimised - see Why the use of UV treatment reduces the cost of chemicals
Beware of the So-called Experts
Thousands of new Firms have jumped on the Renewable Energy Bandwagon and their Clients have often been sold schemes that just do not work
Bluepools has been involved in quite a few projects where Clients have paid 10's of thousands for Ground Source Heat Pump systems that basically just do not work.
In many cases it is quite apparent that the so called experts are people that have been on a two day course, received a "Certificate of Competence" and have then set themselves up as Renewable Energy Consultants or Installation Contractors.
The extent of the problem was greatly exacerbated by the Governments "Feed In Tarrif" scheme that was designed to encourage uptake of a range of small-scale renewable and low-carbon electricity generation technologies.
The tariffs have now been reduced to such low levels that most of the cowboys are moving on - but many of the people that bought into their schemes have been left with systems that do not work at all or work very badly.
Swimming pools use a lot of energy and so Clients should seriously consider investment in equipment that will reduce CO2 emissions and running costs and require minimal maintenance.
Bluepools Designs the Schemes and ensure that the Capital Cost is returned in Reduced Pool Operating Costs
Such equipment will require significant investment and Bluepools will not only design a scheme that will actually work - but also make sure that the capital cost is returned by reduced operating costs.
Types of Equipment that are available to Harness the Energy that Falls on the Earths surface from the Sun
These fall into three categories that are of practicable use in a swimming pool.
- Air Source Heat Pumps that Heat Water
- Ground Source Heat Pumps that Heat Water
- Photo-Voltaic cells that produce Electricity
Nothing else is viable as direct Solar Heating of water does not workin Northern Europe (Including France) because of the unreliability of the weather in Spring and Autumn.
Local Authorities are insisting on "Renewable Energy" heating systems
All these systems should be welcomed by Local Authorities who are insisting on "Renewable Energy" heating systems that will comply with the current Building Regulations.
Both types 1) and 2) are ideal for supplying the required Hot Water to the Air Handling Units that control and regulate the Environment in an indoor pool hall including both air humidity and air and water temperatures.
Roof mounted Photo-Voltaic cells reduce running costs even more but are of course quite costly to install.
Air Source Heat Pumps
Have been in use for a long time
Air to water heat pumps have been successfully installed for many years, especially for providing very efficient pool water heating.
They absorb energy directly from the external air rather then from the earths strata and this eliminates the need for heat collector pipework in the ground.
COP
The efficiency of both air and ground source heat pumps is expressed as number - normally between 2 and 6. This number provides the energy output of the heat pump as a multiple of the energy required to run the electric motors that power the compressor and fans etc within the heat pump.
So a heat pump with a COP of 4 will provide 4kW of energy for every 1kW that is needed to make it work.
Air Source Heat Pump Disadvantages
The disadvantage of air source heat pumps is that the heat pump's coefficient of performance (COP) reduces when the air temperature is low.
During the heating season the outside air temperature is often less than the ground temperature (at a depth at which heat is extracted by a ground-source heat pump). This lower temperature has the effect of reducing the COP of an air source heat pump.
Ground Source Heat Pumps Cost a Lot More
But Ground Source Heat Pumps are a lot more costly to install because of the installation of underground pipework.
There are many types of air source heat pump being sold today and the cheap ones will work on a small outside pool for the summer months and may even last 2 or 3 years and you can rarely get spare parts for them.
Better quality Air Source Heat Pumps provide the Best Value for Money
Better quality Air Source Heat Pumps will provide a lot more heating power and last several times as long - and spare parts will always be available.
Ground Source Heat Pumps
They Collect the Sunlight Energy that Falls on the Earths Surface
These machines provide the means to collect the sunlight energy that falls on the earths surface and is then transferred deep underground by the thermal conductance of the surface layers and rock below.
The transfer of heat down into the deep layers is quite slow and as a result the temperature of the ground about 20 metres below the surface is constant all year round no matter how much the temperature of the surface layer varies between summer and winter.
The Heat Collector pipework can be installed in shallow excavations or in deep boreholes
The Heat Collector pipework can be installed in shallow excavations where the heat energy available will be high in the summer and low in the winter or in deep boreholes where the heat energy availability is constant throughout the year.
The deep borehole are a lot more complicated to design and install - get it wrong and the ground will freeze up!
The deep borehole options are much more expensive than the shallow borehole option and are a lot more complicated to design and install.
If the borehole is not deep enough and the ground around cannot provide enough energy to sustain the the transfer rate of the Ground Source Heat Pump the rocks around the borehole will get colder and colder until the ground freezes and the heat pump stops working!
Open Loop and Closed Loop Systems
There are two basic options in deep borehole GSHP installations. These are known as Open Loop and Closed Loop.
In an Open Loop system there are two boreholes at least 7 or 8 metres apart and water is pumped up from one borehole, through the GSHP and down into the the second borehole where it is dispersed back into the ground.
In a Closed Loop system there is only one borehole and a pipe that goes down to the bottom and back up to the top and water is pumped through the pipe and through the GSHP where the heat energy is extracted.
It is easier to get consent for Closed Loop systems because there is no actual removal of water from the underground aquifer.
In most cases Open Loop Schemes will require a licence that is issued by the Environment Agency
The design process is complex and easy to get wrong if carried out by anyone who is inexperienced or qualified
The design of both types is dependent on the thermal conductivity of the rock into which the borehole is driilled and the thermal conductvity depends on the water content of the rock and the groundwater levels and gradients - so the design is complex and easy to get wrong if carried out by inexpereinced people.
Bluepools Designs and Manage the installation of Ground Source Heat Pumps
Bluepools can design and manage the installation of Ground Source Heat Pump Schems and make sure that the heat output exactly matches the requirement of the Air Handling Unit within the Pool Hall.
Photo-Voltaic cells that produce Electricity
There are two types that can be used on the roof of a Pool Hall and they are:-
- Building Integrated Photo-Voltaic cells
- Photo-Voltaic cells
BIPV cells actually form the waterproof layer of the roof.
Conventional PV cells are fixed above the tiles or slates of the roof with fixings that are designed to maintain the weatherproofing of the building.
BIPV roofs are quite costly but can provide a loot of power up to a maximum of about 7kW per square metre.
Romag were the pioneer for these systems