Diskussion fra 2016 af energiforsyning til en overdækket udendørs pool

NB: noget anderledes situation: det var i 2016, og det handlede om en udendørs-pool med biologisk rensepool.

Requirements, clarification of typical usage:

·  Outdoor pool

:  Mainly one person using the pool 

·  1/2 - 1 hour use every morning around 7am 

·  Covered 23 hours a day - either as a close fitting cover or as a large glass enclosure of the entire space. 

·  Water surface of 5 m by 2,5 m; depth at least 1,6 m, 

·  CHANGE:  28C in morning

·  Ideally 365 days-a-year usage, Optional: Mar-Dec (incl.), 

My questions from 2016; with energy consultant's responses in blue

1.       Which solutions, single or hybrid heating sources, would satisfy the above requirements? And how? Specific sub-questions:

1.       Which solution is recommended - and why?  

The calculation showed that it will take during winter time approx. 3.500 kwh/month of heat energy. That means approx. 100 kwh/d. 

To Produce 100 kwh heat energy per day with an output heat temperature of 50 °C on the primary side it will take approx. 30 Kwh electrical energy if we use an heat pump (geothermal ). In case that we use an Air heat pump I assume that we will use approx. 40 kwh/day during the winter time. 

Over the whole year 27.000 kwh heat energy will be used that would cause an electrical energy demand in terms of the ground heat pump of approx. 7000 kwh (0,2 €/kwh = 1400 €/a) and an air heat pump of approx..: 10.000 kwh (0,2 €/kwh = 2000 €/a)  

2.       The heat pump should have an power of approx.. 10-15 kw

 

3.       Is there an upper limit to how much a heat pump (air to water) can raise the temperature. I think I saw +10 C mentioned; elsewhere I saw minimal operational temperatures mentioned. What are the technical specs? All heat pumps are more efficient in cases of low output temperatures. We should work with 50 °C on primary side which is ok for the heat pump. If the temperatures are lower we have to work with a very big heat exchanger.

4.       What kind of addl. requirement to control of heating sources arise from this particular application? Like, need to have max temperature in the early morning, and we will work with a micro controller were you can control the temperature via an internet platform

5.       Assuming we need to supplement with another source, would solar->water be an option? And what kind of performance can we get from a hybrid setup. As calculated in the modulation solar is an option but only in cases that we use vacuum pipes. In the calculation approx.. 8.400 kwh heat energy will be produced with the solar modules which save you approx. 2500 kwh electrical energy (0,2 €/kwh = 500 €/a) . The plant with 15 m² will cost approx. 8.000-12.000 €

2.       How would we calculate the annual cost of fuel? Or just amount of kWh? This has been calculated with the simulation already see above E solar plus E aux are approx. 27.000 kwh. We assumed that the basin is insulated with 100 mm PU foam and covered with a floating membrane. We assumed that the pool is opened during 1,5 h/day in the morning time. The temperature is always between 27 and 33 °C

 

3.       How do we assess the cost-benefit of a glass covered room for the pool - in addition to a floating pool cover?  A thermo roof can reduce the heat losses approx. by 20 %.

4.       How would the pool heating function in case of occasional "party or family use", e.g., having the pool uncovered for 4-5 hours? (NB, this is NOT a design requirement; just asking from curiosity) it depends very much to the air temperature. You can take in to account a temperature reduction of 0,5 °C per h when the air temperature is approx.. 5 °C and wind is approx. 0 m/sec

The setup I had discussed with energy consultant back then was an air-to-water heat pump as primary heat source, supplemented by some solar water heating. However, his report stipulates a 60kw gas heater; was that because a heat pump couldn't make it work? No the heat pump is an option. We would design it in a smaller scale to get higher running times. As shown before.

 

Some detailed questions to the report:

• Why is the total energy consumption different in the two ends of the chart called: Solar energy consumption as percentage of total consumption? The total consumption will be approx.. 27.000 kwh/a approx. 8000 kwh of this demand can be provided by an 15 m² solar generator.
• What are the two spikes in the chart called: Daily maximum collector temperature? In this time zones the pool reached higher temperatures than 33 °C therefore the generator runs without heat transport which produce an high temperature in the generators.
• Is the calculation of annual energy consumption of 30000 kwh assuming that the pool is covered? If yes, which cover option: glass enclosure of the entire pool area, versus putting a top on the pool, versus "just" having a cover float in the pool? Floating membrane with 100 % covered 22,5 h per day in a protected area.