Checklist: Insulation

[puntloos]

Since there is a checklist: Heating, should we not have an insulation checklist? 

Does anyone have one? Which design features should a house have to make sure that the overall insulation (achieved by good walls filled with sufficient insulating material) isn't wasted by a few cold bridges or other gaping holes, physically or metaphorically?

 

A few technologies, techniques points I'm aware of:

 

- (minor) Heat insulating wall ties

- (major) Avoiding cold bridges (who will check if my house design has 0? 1? 10? cold bridges? Will a SAP calculation do it? Will PHPP show such a design flaw?)

- (major) Hit sufficient airtightness levels (but which techniques do you use? Or is this a yes or no thing?) 

- (medium) door threshold design

 

.. etc

 

Does anyone have a proper list, or want to add to mine?

[MikeSharp01]

5 hours ago, puntloos said:

Will PHPP show such a design flaw?

Only in big picture terms, you need to show how each detail works and find the values to plug in yourself (or your architect / PHPP Consultant does).

 

 

[SteamyTea]

https://en.wikipedia.org/wiki/Thermal_diffusivity

 

Just a measure of how much area a heat wave will travel in a set time.  The smaller the number the better.

Brick is 0.52 mm².s^-1

Wood is 0.082 mm².s^-1

 

 

[puntloos]

3 hours ago, SteamyTea said:

https://en.wikipedia.org/wiki/Thermal_diffusivity

 

Just a measure of how much area a heat wave will travel in a set time.  The smaller the number the better.

Brick is 0.52 mm².s^-1

Wood is 0.082 mm².s^-1

 

Sure, so if I make all my walls and windows and doors and cold bridges out of wood I will be good?

But seriously, I understand that for example while it is likely to be a good idea to have triple glazing it might not be necessary to hit a certain U value. So certainly, some decisions depend on what you need to achieve, but some decisions I imagine are probably *always* a good idea, or at least worth considering and/or checking.

 

Is there a "passivhaus for dummies" list?

 

 

[SteamyTea]

45 minutes ago, puntloos said:

 

Is there a "passivhaus for dummies" list?

AKA basic engineering.

45 minutes ago, puntloos said:

a good idea to have triple glazing it might not be necessary to hit a certain U value.

There is a certain fixation with U-Value. This is mainly to do with legislation.

The main thing, that usually gets forgotten, us that it is to do with thermal losses, and therefore energy consumption.

So it is better to look at what you want to achieve in that area, then work to it i.e a north facing wall, which never gets solar radiation in it  should have lower U-Value to counteract.

Edited November 14, 2021 by SteamyTea

[puntloos]

32 minutes ago, SteamyTea said:

AKA basic engineering.

 

Not sure that's fair. For perhaps the threshold design, any good threshold would be near airtight vs one with sloppy engineering, sure.

 

But the best example I have is the Low conductivity thermal wall ties thing. Not sure they will make a *huge* difference (maybe not at all!) but I imagine a house could be properly engineered but the designer in question, not being aware these exists, would have just shrugged and chalked that heat loss up to business as usual.

 

32 minutes ago, SteamyTea said:

There is a certain fixation with U-Value. This is mainly to do with legislation.

The main thing, that usually gets forgotten, us that it is to do with thermal losses, and therefore energy consumption.

So it is better to look at what you want to achieve in that area, then work to it i.e a north facing wall, which never gets solar radiation in it  should have lower U-Value to counteract.

 

Sure, but there are multiple ways to get there. It's all a balance of course, you could have super expensive insulation material X with amazeballs U-value Y, or you could have a house that doesn't have that many cold bridges. 

 

Individually all these tradeoffs make a lot of sense once you point them out. But especially as a layman I'd like to do at least some due diligence on which tradeoffs even exist (because I don't know what I don't know)  

[Iceverge]

14 minutes ago, puntloos said:

But the best example I have is the Low conductivity thermal wall ties thing. Not sure they will make a *huge* difference (maybe not at all!) 

 

They don't

 

 

[puntloos]

3 minutes ago, Iceverge said:

They don't

 

Helpful to know, thanks. But as an example it somewhat stands. Perhaps one way to think about this is:

 

Which design choices yield the best cost per heating cost saved? As per your example, wall ties therefore cost 2500 to save 2.. not.. great.

 

Of course cost saving isn't the only driver, just doing 'the right thing' (plus not having a draughty house with cold spots).. 

 

 

 

[joe90]

I opted for double glazing with coatings that was very near triple glazing levels as I don’t like heavy bulky window frames., also I used ordinary wall ties.

[puntloos]

2 hours ago, joe90 said:

I opted for double glazing with coatings that was very near triple glazing levels as I don’t like heavy bulky window frames., also I used ordinary wall ties.

 

Yeah, in my case I figure that having triple and built-in shutters is probably the way to go, but I'm with you on the bulky part. Saw one at a friend's and didn't figure it was too bad.

[Marvin]

3 hours ago, puntloos said:

 

Which design choices yield the best cost per heating cost saved? As per your example, wall ties therefore cost 2500 to save 2.. not.. great.

Somewhere on the list should be reducing wasted space and avoiding vaulted ceilings.

[JohnMo]

Voulted ceilings depend on the design, our lounge is voulted, to be non voulted I would have to install a ceiling, so that is a cost adder, we are in a bungalow, so the loft would be huge and mostly a waste of space.  With the voulted ceiling the airtight aspects were easy also.  In fact all the ceilings match the roof line, it made the build simple

[ProDave]

21 minutes ago, Marvin said:

Somewhere on the list should be reducing wasted space and avoiding vaulted ceilings.

We chose vaulted ceilings because planning here demands a room in roof situation if you want 2 storeys.  Vaulted ceilings with gable ends and roof hung from ridge beams gives maximum usable space in the loft rooms.  And then insulating them as a warm roof is by far the easiest way to detail a well insulated and air tight roof structure, which puts all the space in the house inside the insulated air tight envelope.

 

I would do it again and go so far as saying the warm roof all inside the insulated envelope was one of the best design decisions we made.  There is NO WAY I would want to do another build that tried to keep the loft space as a cold (and necessarily ventilated) space and still hope to get good air tightness and insulation.

[Marvin]

40 minutes ago, ProDave said:

There is NO WAY I would want to do another build that tried to keep the loft space as a cold (and necessarily ventilated) space

+1

I was really thinking of high ceilings as they require much more heat above your head to achieve the lower room temprature.  

 

[ProDave]

3 minutes ago, Marvin said:

+1

I was really thinking of high ceilings as they require much more heat above your head to achieve the lower room temprature.  

 

Inside a well insulated air tight house, differential temperatures within the building really are a non issue.

 

e.g. I can go up into the little bit of enclosed loft space we have, which is not heated in any way and has no deliberate air flow through it, but is within the air tight and insulated envelope, and is it just as warm as any other part of the house.

 

Upstairs in the one bedroom that has the vaulted ceiling all the way up to the ridge, I can go up onto the mezanine level and it is no warmer than down at floor level.

 

I think what is happening, is without the building losing heat, you don't get the convection circulation you get in an old leaky house.

[puntloos]

8 minutes ago, ProDave said:

Inside a well insulated air tight house, differential temperatures within the building really are a non issue.

 

e.g. I can go up into the little bit of enclosed loft space we have, which is not heated in any way and has no deliberate air flow through it, but is within the air tight and insulated envelope, and is it just as warm as any other part of the house.

 

My PHPP/SAP calculator guy says he needs to know 'right now' if we are heating the loft or not. 

 

He says: "If the top floor is not then heated,we need to think about insulation adjacent to this unheated space."

 

Is this even true for a super-well-insulated house? I assume(d) that if you have UFH in G+1fl you don't even need to heat the loft?

 

 

[ProDave]

10 minutes ago, puntloos said:

 

My PHPP/SAP calculator guy says he needs to know 'right now' if we are heating the loft or not. 

 

He says: "If the top floor is not then heated,we need to think about insulation adjacent to this unheated space."

 

Is this even true for a super-well-insulated house? I assume(d) that if you have UFH in G+1fl you don't even need to heat the loft?

 

 

If you are doing PHPP I assume you are aiming high.  We only have UFH downstairs and no heating upstairs, and the bedrooms, the mezanine and even the enclosed loft space all remain warm, because they are within the sealed and insulated envelope.

 

To my mind it is madness to try and exclude a loft space from the sealed and insulated envelope because it just gives you a whole host of extra details to insulate and make airtight, not least being the loft hatch.

[Marvin]

22 minutes ago, puntloos said:

 

My PHPP/SAP calculator guy says he needs to know 'right now' if we are heating the loft or not. 

 

He says: "If the top floor is not then heated,we need to think about insulation adjacent to this unheated space."

 

Is this even true for a super-well-insulated house? I assume(d) that if you have UFH in G+1fl you don't even need to heat the loft?

 

 

Well I don't know the design of your home, but it is called the thermal envelope so any way the heat can transfer out of your building will need to be insulated. All 6 surfaces of a cube...

Edited November 14, 2021 by Marvin
Clarification

[Marvin]

6 minutes ago, ProDave said:

the loft hatch.

Another problem I'm yet to solve!