energy efficient homes

[buildit1]

I'm not 100% sure on the exact setup that he has, but I think he uses the GSHP mainly for hot water and he has some other heat pump for a ventilation system that heats the home.
Maybe he didn't need the other thing with the GSHP, but I don't know at the minute.
Do you have a link of where the info is on u values.

 

[stevethejoiner]

electric heat pump among other things.

[/quote]

I think he may mean electric heat recovery unit

 

[Nbishara]

If you haven't found it already, I'd highly recommend the aecb (association of environmentally conscious building) forum for these sorts of discussions. You might also want to get into the passivhaus planning program spreadsheet. As I understand it, it's complicated, but it allows you to play around with the parameters (such as depth of insulation) and see what happens. ...and you don't have to be aiming for passivhaus to use it, obviously.

Coming back to expanding foam, I don't think anyone mentioned the potential issues of outgassing and environmental impact of propellants. I'm no expert on either, but I'm aware that they have certainly been issuessfor some foams in the past.

Good luck with the build anyway. Whatever you save on fuel now will only increase in the future as energy prices rise and besides, the greenest energy is the energy you don't use...but you already know that by the sounds of things...

Tania

 

[mointainwalker]

but I'm aware that they have certainly been issuessfor some foams in the past

Correct, but as you say that was in the past. Propellants and foaming agents which were very ozone- reactive have been banned for quite a few years now.

 

[buildit1]

Nbishara.

I have recently read about a Passivhaus that had been built for a couple, called the Denby Dale project. The one thing I noticed, was that it had 300mm of insulation fitted.
I appreciate the feedback from people on here, but as I don't yet understand how to calculate the U values in comparison to heating costs it's pointless in me carrying on this discussion.
I'm going to wait until after the new year and speak to a few companies that deal specifically in low energy homes and see if I can get some more advice on the insulation side of things.
I'll have a look at the other forum and spreadsheet you suggest.

Many thanks.

The bottom line on what I am trying to find out is how to construct the most energy efficient house. Insulation is only one part of it, but I'd like to know every individual thing, so I can then calculate what are the most cost effective ways of doing it.

Thanks all.

 

[mointainwalker]

Insulation is only one part of it, but I'd like to know every individual thing, so I can then calculate what are the most cost effective ways of doing it.

Very laudable but until you understand the basic principles , not possible. You need to search and read about u values so you understand what it is and how that can be used.

 

[jeds]

Understanding u-values is relatively straighforward but that alone will not enable you to make a meaningful calculation of general energy efficiency. Take the thickness of roof insulation. 30 years ago 50mm or 100mm was considered sufficient. It was then a relatively expensive material and fuel was relatively cheap so it probably was enough. But that has obviously now changed and as fuel costs rise it will change again. These days mineral wool is so cheap fitting 300 or 400mm is a no-brainer and I've seen plenty of projects with 500mm.

The only way to really calcuate energy efficiency is to use a whole house SAP calculator. There is a free one available from Complete Picture that will give you a full calculation but you can't print anything off. But even then the factors are complex and, unless you know what you are doing, coming up with an efficient solution is not easy.