New build and renewables - where do I start?

Dr. Nick

We hope to start building a new house in the countryside later this year, I was wondering what our options are.

At the moment I’m thinking of either a pellet burner or Geo-thermal, with solar for domestic water heating.

The cost of Geo-thermal seems high, what are the experiences of it here? How does it compare to pellets?

Also (apart from here!), where can I get good independent advice on all of the options available (preferably actually speaking to people rather than reading websites)?

No6

Start with the more passive measures more insulation & less air escaping and better windows before you spoend a fortune on any form of renewable but why are you considering two types together very very expensive

CJhaughey

Do you have a house design in mind?
What construction method will you use?
What is the projected heatloss from your house?
Will you fit Dormer windows or Velux?
Are you going to use passive solar in your house design?
Is the site S. facing?
Can you face a section of the roof to SE-S-SW?
Is the site suitable for GSHP? Rock, Bog, Soil?
Will you install a HRV system?


Before you start looking at ways to heat your house you need to see if you need to have Heat at all.
If you build to Passive house specs then you will not need a GSHP.
Solar DHW is normally fitted in this type of house.
I would start with the house design and position and construction first THEN start looking at heating options and water heating options.

Dr. Nick

Do you have a house design in mind? Already designed and approved - dormer.
What construction method will you use? Probably timberframe
What is the projected heatloss from your house? don't know
Will you fit Dormer windows or Velux? both
Are you going to use passive solar in your house design? what's that?
Is the site S. facing? all living areras south facing, with large full-heigth windows 3.5m wide in dining area. windows extend to roof so upstairs gets light too.
Can you face a section of the roof to SE-S-SW? yes
Is the site suitable for GSHP? Rock, Bog, Soil? What's GSHP? Soil not rocky or boggy.
Will you install a HRV system? What's HRV?

CJhaughey

Well you are not going to build a passive house.
So you will still need to know what kind of heating demand you require.

This can be drastically reduced by fitting high quality doors and windows and paying very close attention to detail as they are fitted, which means having insulation up to the window frame and not large gaps filled with plaster!
Secondly fitting Heat Recovery Ventilation (HRV)will enable you to make the structure airtight or as near as you can without the need for wallvents/window vents etc all of which make your house draughty and hard to heat.

HRV is mechanical heat recovery ventilation, an airpump that introduces fresh air into the house and removes stale air from the house.
During this process it takes heat from the outgoing air and uses it to heat the incoming air. This is perhaps the single biggest difference you can make to a house, without this you are required by law to have sufficient ventilation in every room,typically by having a hole in the wall!

Velux and dormers are a net heatloss from a house, basically a hole in the roof.
Dormers can be very cold as the detailing of the dwarf walls means that they are very hard to insulate properly.
Better to have fewer larger Velux then lots of small ones.

Passive solar is using the house orientation to maximise the heat gain from the sun.
It sounds as though you have already done this to a degree.
What do you mean when you say windows extend to roof?

Solar DHW is good IMO we have a SW facing roof 6m2 of flat plate collectors and a 400l tank.
Yesterday the tank was over 60º from the sun this is run through a mixing valve to ensure the water does not reach the taps hotter than 45-50º to ensure no risk of scalding.
The benefit of this means that a 400l tank of 60º water is actually more like 600-700l of 45º water once it has been mixed.

Geothermal is not really a correct name for what you are talking about.
Regarding Ground Source Heat Pumps there is a sticky that has info on these systems at the top of this page.
You may be able to utilise an air to air/water heatpump if your house is designed and built with attention to detail.

Dr. Nick

Thanks CJ, great info.

CJhaughey wrote: »

Passive solar is using the house orientation to maximise the heat gain from the sun. It sounds as though you have already done this to a degree.
What do you mean when you say windows extend to roof?

We have the glass running up into the roof, the effect of which is to have glass instead of roof on a section upstairs looking over the landing and hall below.

pete6296

Hi,
I have the same feature, talll glass section but up along roof we fitted the largest velux that can be bought that can be opened with remote. Cost 2,500 in comparison to 7k for roof glazing.
Just an idea for you to consider.
Pete

Dr. Nick wrote: »

Thanks CJ, great info.




We have the glass running up into the roof, the effect of which is to have glass instead of roof on a section upstairs looking over the landing and hall below.

Dr. Nick

pete6296 wrote: »

Hi,
I have the same feature, talll glass section but up along roof we fitted the largest velux that can be bought that can be opened with remote. Cost 2,500 in comparison to 7k for roof glazing.
Just an idea for you to consider.
Pete

Thanks Pete, I'll keep that in mind.

CJhaughey

Just be aware that if you have good insulation that the summer sun can produce large amounts of heat through windows that can make it very uncomfortable.
We have 12m2 of glazing to the SW comprising 6 2x1m windows and this in the full summer sun needs to be managed well to ensure that the house does not over heat.
We have 500mm of overhang with the eaves but this is still not enough, we also need to pull blinds.
Just be aware of excessive solar gain.

Dr. Nick

CJhaughey wrote: »

Just be aware that if you have good insulation that the summer sun can produce large amounts of heat through windows that can make it very uncomfortable.
We have 12m2 of glazing to the SW comprising 6 2x1m windows and this in the full summer sun needs to be managed well to ensure that the house does not over heat.
We have 500mm of overhang with the eaves but this is still not enough, we also need to pull blinds.
Just be aware of excessive solar gain.

Yeah, sounds like auto-blinds will be required for upstairs.

Hector's House

I'd highly recommend you look these people up. Was at a viewing of a passive house under construction near Ashbourne yesterday. They plan on having monthly open days as it's completed. Very impressive, both in the thought given to every aspect of the energy efficiency of the build, as well as the emphasis on quality - something sadly lacking in this country!

http://www.german-eco-homes.ie/
http://www.german-eco-homes.ie/invitation.pdf