Energy efficient new build
 

We are in the process of completing a new build here in Spain. It is around 140 M2 (1500 ft2) in size and although the plan wasn't to employ any new technology in its construction I wanted to try to make it as energy efficient as possible.

The climate here varies considerably during the year although it rarely goes below freezing we do have several fairly cold months and very strong winds that can have significant impact on the heating of the house. Summers can get up to 40C although typically they are around 35C daytime and 25+ C night time.

The 'house' that was on the site where we have built was a typical Spanish mess of a 150+ year old stone boulder+mud+whatever else was around roughly 15M2 with 1.5M thick walls making the usable space little more than space for a bunk bed.
http://ecorenovator.org/forum/attach...1&d=1434546508

Then there was a very small bathroom/shower, a lounge kitchen and 2 bedrooms. These were bits added on at various times with a mix of (all un insulated) roofs at different angles with leaks :-( On the back was a water store with a huge crack that meant it could only be half filled and a boiler room with a low door (I hit my head many times!) and a wash room.

All ok for the summer but very hot and in the winter extremely cold as it faces into the prevailing wind.
http://ecorenovator.org/forum/attach...1&d=1434547011

The new build occupies pretty much the same area as the old bits but has a much better distribution of the rooms. There are 2 bedrooms, 2 bathrooms, kitchen, lounge, sun room and wash room, I moved the boiler out for reasons that will become clear later.

The old buildings were all demolished at the beginning of November 2014.
http://ecorenovator.org/forum/attach...1&d=1434547458
http://ecorenovator.org/forum/attach...1&d=1434547458

Acuario

I used a program called 'Home Plan Pro' to design the house - it is sometimes a little awkward to use but given its low cost I can't complain.

The external walls are 200mm concrete block with reinforcing bar every meter or so. The drain for black water goes to the septic tank and for grey water from the showers and washing machine to a soak away that runs along side some oleander bushes - no need to water them!
http://ecorenovator.org/forum/attach...1&d=1437894826
In the background you can see the new water deposit (16,000 litres more or less), the grey door on the left is the new boiler room - you can see the 3 solar hot water panels on the roof above, set at winter angle for maximum heat - these are linked into the central heating system along with the (also visible) home made heat pump. The orange marks on the wall are for 2 new connecting doors, the small door is obsolete and has been removed.

http://ecorenovator.org/forum/attach...1&d=1437894826
http://ecorenovator.org/forum/attach...1&d=1437894940

Everything here is built from concrete and steel, very little wood as it is expensive and tends to get eaten by the local bug population. It amazed me how much steel we ended up putting in the roof - see the image. It took 4 of us 2 days to prepare it for its concrete. We then used 14 cubic metres of concrete to give an approximately 6cm thickness. The hole at bottom left is for a wood burner chimney. There is also a hole for a roof ladder so all the roof space can be used for storage, something the Spanish don't typically do.

Acuario

Although Spain is a (theoretically) hot country there are building requirements for insulation for energy conservation.

The inside of the walls were all sprayed with expanding polyurethane foam insulation to a depth of 5cm. I also took advantage of the space to run corrugated tube trunking all around for the electrics. The inside walls were then built against the insulation and building foam injected into the spaces to bond and infill the space between the foam and interior walls.

Next was the under floor heating tubes and manifold. Each room has its own circuit and valve.
http://ecorenovator.org/forum/attach...1&d=1437895056
The floor panels are 40mm deep and have 5cm of cement with a plasticizer on top, then floor tiles to finish it off.

There are 2 parts to the roof so that it matches in with the existing roof. Part is pitched and part flat. On the pitched part there is 7cm of insulation and on the flat part 9cm of insulation.
http://ecorenovator.org/forum/attach...1&d=1437895056

http://ecorenovator.org/forum/attach...1&d=1437895056

Acuario

I could only view the pictures in the first post, but what I can tell of what you are doing sounds good. There aren't enough people around where I live who care about efficiency nearly as much as they do the initial expense. I'm sure it will pay off versus the building you removed. keep up the good work!

I didn't see what your energy consumption was, but it would be interesting to have a word when the project is finished to compare the amount used for the original dwelling and the new one as well as the difference in actual living space.

Not sure what happened to the pictures the first time but I've added them again and they are now visible.

Because of the radical changes both in size, distribution and construction any comparison would be meaningless. What I can say is that the old build was a fridge in the winter and an oven in the summer. The couple of months that we had the heating connected on the new build kept the whole building at a very pleasant 21C. This summer (one of the hottest in the last 25 years so they say) the temperature inside has not gone above 26C on the hottest side of the building.

With the heat-pump that I've built and the overnight cooling with fans that are only for the old build where there is no under floor cooling (see other threads) we are keeping the whole new build (140m2) plus our lounge where I installed under floor heating last autumn (another 50m2) cool with a miserly 1.5Kw energy consumption.

The temperature in the old part of the house which is cavity wall insulated but has no roof insulation gets up to 28C during the day and cools to typically 26C overnight, outside daytime temperature has been ranging between 35C and 39C.

Acuario

Awesome job like usual! I'm sure the concrete has lots and lots of thermal mass to help keep the indoor temperature stable.

Great build progress!

How have things progressed?

It's pretty much finished now. Interestingly this summer was the hottest for the last 30+ years with temperatures near 40C for most of June, July and the beginning of august but inside with no cooling the temperature didn't raise above 26C so I'm very pleased with the results so far.

We'll see how things go in the winter which normally starts around the end of November. The home made heat pump has had a few minor mods with a bigger heat exchanger and checking it out on cooling (we used it for cooling the floor in the old house which made a huge difference when combined with the fans in the windows upstairs) it was consuming 1.5Kw so pretty efficient.

The combination has meant this has been the coolest summer I've had in the house in the 11 summers I've been here which is incredible as it has been a very long hot summer - the wife even complained she needed a blanket at night!