Wet underfloor heating is by far the most efficient to run - especially when combined with a renewable energy source such as a heat exchanger or solar panels.
If your electric underfloor heating is running at full (which it will until it reaches the desired temperature and then it typically runs at 40%) it will consume about 0.15KW per hour per m2 for your surface area.
For instance to heat about 200m2 would take approximately 30KW at a worst case.
The EDP in the Algarve charge about 0.12 cents per kw and 200m2 on full capacity will cost you around €3.6 per hour. This means your energy bills could top €1000 per month (this does depend on the thermal efficiency of the house, when you put the UFH on etc). ...so your return on investment for the wet UFH can be within 1-2 years.