Solar and air source heat pumps/and insulation/

I am considering buying a half built house in spain The basic structure is up . ie concrete frame, walls and the roof is on. It is about 8 years  old and not well insulated no windows or door no internal partions and floors are not screeded. Its a large property approx size 170m basement aprox 2.5 m deep into ground. 170m x 2.6m high ground floor and 130m  x 2.6m high 1st floor. It is not yet renderd inside or out. I am at a very early stage working out costs ect. I have some experience extending property and  putting in pool in spain on my existing holiday property. ( this will be a live in property)

The rooms are very large and I would not miss say 100mm of space from the inside of the external walls I would like to install underfloor heating and cooling all run off an air source heat pump whitch in turn would be run off solar pannels. with mains back up.

I have been looking at air sorce heat pumps in the uk and they seem to be comming down in price quite rapidly and increasing in efficeny. I would of thought they were the ideal option for spain with the hot weather in summer to drive the solar and cooling of heat pump and not extreamly cold in winter for the heating. 

Is there anyone out the with recent experience of heat pumps installed in spain any Knowledge would be welcome as I would want the heat pump in reverse to cool in summer and then heat in winter I presume I would need seperate solar hot water for summer?

I am thinking should i insulate the house with metal stud and insurlation board and dry line from the inside or insurlated render from the outside  any comments welcome.

I dont know yet how well the basment is waterproofed if at all any advise on water proofing basment would be welcome. Also as the basement is 2.5m into the ground would I be likley to get large amounts of heat comming into the property from the ground?

All comments welcome execpt about spelling lol.

I have built a few properties in the UK and also took on a few unfinished project's..the project that you are thinking about taking on sounds pretty big and in my opinion should only be considered by a experienced builder ..but just to give you some idea of how I would go about it...I would find out how much similar properties are selling for ..I would then add the cost of completion of the property on top of the purchase price if the completion price came in at around 25% less than I could buy a basic similar one for then I would consider it ...your proposal of heat source pumps/solar heating should then be factored in on top the equation after you get a complete price for a basic house...your property at the end of the day with all the proposed extras  is going to cost more than the same looking house next door ..and when it comes to selling your on it will probably go for the same price as the one next door due to the fact that people only take face value into consideration when purchasing .

I have a pool heated by a ground heat source through a heat exchanger.  It is 5kw output. I have not found it too sucessful as a pool heater because the source heat is lower than the desired temp. Even when it is hot outside it takes days to raise water temp. I am talking only about a source to heat the pool

I had an AngelFire heat pump installed about 12 years ago and it's brilliant.  It's remarkably effective if you use it just at the warmer parts of the day, say from 10.00 to 16.00 and you put your insulation bubble wrap cover on at all times you're not actually using the pool, not just at night.

Slightly off-topic, but we're having a new house built in the UK, and we're going to use an air-source heat pump for heating/cooling, as there's no gas supply. We're also going to have about 7 kWp of solar panels. The heat pump will be used for heating water as well. It's made by LG, and I daresay something similar is available in Spain. It can also heat and cool at the same time, so you could cool a warm room (e.g. kitchen or south-facing room) at the same time as warming a cool one (e.g. north-facing room). The excess heat absorbed by the a/c side is used first for underfloor heating or hot water before the surplus being rejected to the atmosphere via the condenser, so we're expecting it to be quite efficient.

I believe water source heat pumps are more efficient than air source, so if you'll be having a pool, it may be worth while considering using that as a heat source/sink, as gjohnint mentions below.

popag: INSUL:ATE< INSULATE< INSULATE, to paraphrase a popular TV program!

My deluxe, castillo, bungalow, shed (whatever you want to call it) is insulated everywhere. The roof void has 100mm of polystyrene (most of it re-used, salvaged from the bins/tip from new domestic appliances) FREE.

The inside of the external walls are lined with 50mm "Styro-Dur" (other flavours available) which is 50% more thermally efficient than polystyrene sheet. Stuck to the bare wall with sticky silicone and then that was clad with 13mm plaster board.

The floor was also layered with the Styro-Dur and then covered with ceramic tiles. You can walk on Styro-Dur without it deforming unlike polystyrene.

So, the result is: we use very little wood in the log burner, we tend not to use it until about 6 weeks after others do. The A/C if far more efficient because of minimal heat loss to the outside.

There IS a downside: In the summer, when it's hot outside and you've had the windows and doors open, then it cools downd outside, the heat gets trapped inside the house so you don't get the benefit of the drop in temperature outside.

Before you spend thousands on expensive stuff, do the cheap basics.

Good luck