Green Building Forum - EPS vs. PIR Sat, 31 Oct 2026 04:23:29 +0000 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170482#Comment_170482 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170482#Comment_170482 Sat, 16 Mar 2013 17:39:34 +0000 Shevek
150 mm Grey EPS = 0.18 u-value = £400
150 mm PIR = 0.15 = £600

Financially the PIR is a no brainer. So it comes down to:
1. CO2 emissions savings of 0.18 vs 0.15
2. Environmental impact of EPS vs PIR
3. Stability of EPS vs PIR
4. Longevity of EPS vs PIR
5. Risk of rising damp at ground level where we potentially create a problem due to lack of breathability.

So let the games begin... how do they compare?]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170483#Comment_170483 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170483#Comment_170483 Sat, 16 Mar 2013 17:39:52 +0000 Shevek
Furthermore we're interested in EnerPhit not as just as an arbitrary energy efficiency standard but as a comfort standard. So, for instance—in order to avoid convection currents and hence draughts—we want to be able to keep all surfaces in the house at 17 degrees or above without being hugely reliant on heating.]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170486#Comment_170486 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170486#Comment_170486 Sat, 16 Mar 2013 18:09:58 +0000 Milk_No_Sugar
Happy to have been of assistance.:wink:]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170518#Comment_170518 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170518#Comment_170518 Sat, 16 Mar 2013 21:40:04 +0000 Seret Posted By: Shevek
1. CO2 emissions savings of 0.18 vs 0.15


Depends on several other factors (HDD for your location, type of heating system, its efficiency, it's carbon intensity).

That difference in u-value will mean about 50kWh of extra heat would leak out for 2000 HDDs. For a 90% efficient gas boiler you'd be looking at about 10kg CO2e per year difference.

So probably about what a hedgehog would fart in that same year.]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170519#Comment_170519 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170519#Comment_170519 Sat, 16 Mar 2013 21:50:03 +0000 tony EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170522#Comment_170522 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170522#Comment_170522 Sat, 16 Mar 2013 22:04:27 +0000 Shevek Posted By: tonyI would say that the breathability of eps would swing it,
For what purpose? Lowering risk of interstitial condensation and rising damp?]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170532#Comment_170532 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170532#Comment_170532 Sat, 16 Mar 2013 23:02:56 +0000 tony EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170566#Comment_170566 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170566#Comment_170566 Sun, 17 Mar 2013 11:14:23 +0000 seascape EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170570#Comment_170570 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170570#Comment_170570 Sun, 17 Mar 2013 12:05:57 +0000 jamesingram So probably about what a hedgehog would fart in that same year.
Fantastic abstract realism :bigsmile:]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170572#Comment_170572 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170572#Comment_170572 Sun, 17 Mar 2013 12:09:15 +0000 DarylP but otherwise, I don't think so.....:confused:]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170573#Comment_170573 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170573#Comment_170573 Sun, 17 Mar 2013 12:10:41 +0000 Nick Parsons EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170578#Comment_170578 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170578#Comment_170578 Sun, 17 Mar 2013 12:19:13 +0000 joe90 EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170580#Comment_170580 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170580#Comment_170580 Sun, 17 Mar 2013 12:27:34 +0000 jamesingram PUR (without foil ) 300 (10,000 with foil, though EWI boards for rendering will be foil less )
EPS 150
Woodfibre 25
Mineral wall 6

from bs12524 water vapour resistance factor
PUR 60 (presume PIR polyisocyanurate is same ?)
EPS 60
wood particle board 5-10
mineral wool 1
phenolic 50

to convert between r and vapour resistance factor see.
"excellent illustration here http://builddesk.co.uk/wp-content/uploads/2013/01/vapourResistances.pdf "]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170583#Comment_170583 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170583#Comment_170583 Sun, 17 Mar 2013 12:41:34 +0000 jamesingram EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170585#Comment_170585 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170585#Comment_170585 Sun, 17 Mar 2013 12:45:46 +0000 Shevek
Am I right in saying there's little difference in breathability from the figures you posted above though? (putting aside glueing sheets)]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170588#Comment_170588 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170588#Comment_170588 Sun, 17 Mar 2013 12:53:54 +0000 RobinB
http://www.passiv.de/downloads/03_enerphit_criteria_en.pdf]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170589#Comment_170589 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170589#Comment_170589 Sun, 17 Mar 2013 12:56:28 +0000 jamesingram (i'm presuming similar value of 300 without foil ?)
though as discussed in Mike George's render breathablilty thread, figures dont tally with BS12524 and sources unclear .
The whole area of breathability of products seems quite muddy to me.]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170590#Comment_170590 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170590#Comment_170590 Sun, 17 Mar 2013 12:59:44 +0000 jamesingram http://www.greenspec.co.uk/insulation-oil-derived.php

One thought not mentioned recently is the long term U value of oil derived foam insulation.
some claim those such as PUR/PIR/phenolic degrade over time through offgassing where as EPS is a stable value.
from greenspec
"Insulation performance can be reduced over the first 3 years due to gas exchange from the cells. This reduction of performance is usually included in the manufacturers declared value of thermal conductivity"
some claims around it's worst than this.]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170989#Comment_170989 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170989#Comment_170989 Wed, 20 Mar 2013 07:32:00 +0000 jamesingram Posted By: ShevekWe're carrying out a retrofit and targeting EnerPhit, and therefore we need to target at least 0.15 u-value to walls. We're restricted to 150 mm insulation because of our existing eaves detail. So the cost to insulate our 35 m2 existing solid brick walls is as follows:

150 mm Grey EPS = 0.18 u-value = £400
150 mm PIR = 0.15 = £600

Financially the PIR is a no brainer. So it comes down to:
1. CO2 emissions savings of 0.18 vs 0.15
2. Environmental impact of EPS vs PIR
3. Stability of EPS vs PIR
4. Longevity of EPS vs PIR
5. Risk of rising damp at ground level where we potentially create a problem due to lack of breathability.

So let the games begin... how do they compare?

1.some , but little, by Seret figure 600kg CO2e over 60 years (life time of refurb (will EWI last that long)?)
2.EPS wins
3.EPS wins
4.EPS wins
5.EPS wins]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170994#Comment_170994 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=170994#Comment_170994 Wed, 20 Mar 2013 08:03:18 +0000 Shevek EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171006#Comment_171006 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171006#Comment_171006 Wed, 20 Mar 2013 10:38:00 +0000 fostertom http://www.natural-building.co.uk/images/downloads/Breathability_in_buildings.pdf actually gives ranges of resistivity values - so EPS not just 150, but 100-750, XPS 600-1500, and PU foam not just 300, but 115-1000. So it's wide open.]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171104#Comment_171104 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171104#Comment_171104 Thu, 21 Mar 2013 00:14:35 +0000 Saint Posted By: jamesingramShevek , have you a product in mind for 150mm PIR/PUR no foil faced , might find it's only available in 100mm max so you'd need to glue board together, which might confuse the issue.
PUR and PIR without foil faces available in thicknesses up to 600mm, in fact I'm not sure if you can't actually get 750mm. The bigger the order the better the price of course]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171114#Comment_171114 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171114#Comment_171114 Thu, 21 Mar 2013 08:40:53 +0000 Saint
11 Water vapour penetration

11.1 The product has a minimum water vapour
resistivity values in the range of 145 MNsg–1m–1
for SD grade to 719 MNsg–1m–1 for EHD grade
and will therefore provide significant resistance to
water vapour transmission. Joints between boards
will facilitate the passage of water vapour under
normal conditions of temperature and humidity.
11.2 If the product is to be used in the external
walls of rooms expected to have high humidities,
care must be taken to provide adequate permanent
ventilation to avoid possible problems from the
formation of interstitial condensation in the internal
wall leaf.

Its not a special grade of EPS, its just made in smaller board sizes to fit in a cavity.

Thermal condiuctivites are given as:

12 Thermal insulation

12.1 For the purpose of U value calculations to
determine if the requirements of the Building (or
other statutory) Regulations are met, the thermal
conductivity ( value) of the insulation board may
be taken as shown in Table 3.

Table 3 Thermal conductivity values
Product Grade Thermal conductivity
(W/mK)
WallShield SD 0.037
WallShield SD lo  0.035
WallShield HD 0.035
WallShield EHD 0.033
MicrofoamX32 — 0.032
WallShield Platinum Neopor NEO 0.031]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171118#Comment_171118 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171118#Comment_171118 Thu, 21 Mar 2013 08:53:36 +0000 Shevek EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171122#Comment_171122 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171122#Comment_171122 Thu, 21 Mar 2013 09:01:46 +0000 Saint EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171125#Comment_171125 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171125#Comment_171125 Thu, 21 Mar 2013 09:11:39 +0000 Shevek EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171131#Comment_171131 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171131#Comment_171131 Thu, 21 Mar 2013 09:54:08 +0000 fostertom
'Significant resistance to water vapour transmission' doesn't mean it's unsuitable for use in 'breathable' construction. It's not all that 'significant' - just 'not near-transparent' as dedicated breather products are. It's still way down the at the low-resistance end of the scale, amongst building materials. As long as the 5x (some say 3x) rule of thumb is applied, so something 5x (or 3x) as resistant is provided inboard, then it should be a safe 'breathable' construction, albeit at a modest rate of 'breathing', but preferrable IMHO to an industry-standard non-'breathing' construction with inboard full VCL.

Having said that, are we sure about
Posted By: SaintIts not a special grade of EPS, its just made in smaller board sizes to fit in a cavity.
My prev researches held up Springvale's Neopor EPS as having particularly low resistance, 50 I think, not 145, i.e. even lower (because Neopor) than the 100-750 range given in http://www.natural-building.co.uk/images/downloads/Breathability_in_buildings.pdf .]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171133#Comment_171133 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171133#Comment_171133 Thu, 21 Mar 2013 10:00:20 +0000 fostertom EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171139#Comment_171139 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171139#Comment_171139 Thu, 21 Mar 2013 10:43:15 +0000 Saint Posted By: ShevekSo it seems to me there's no winner on item 5 (vapour permeability). Both PIR and EPS are increasing the risk of interstitial condensation by similar degrees.
If you want vapour permeable you'll need to look at mineral fibre, Rockwool etc.
No plastic foam is particularly vapour permeable. Kingspan who bought Springvale as part of the CRH acquisition insulation and then let them Springvale go (they didn't want EPS) get very shirty about the whole idea of breathability...well they would do...http://www.kingspaninsulation.co.uk/Knowledge-Base/Breathability-1.aspx]]> EPS vs. PIR https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171143#Comment_171143 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10318&Focus=171143#Comment_171143 Thu, 21 Mar 2013 10:47:59 +0000 Shevek Posted By: SaintIf you want vapour permeable you'll need to look at mineral fibre, Rockwool etc.
That's a thought. Much more expensive though right? Perhaps, however, we could use a strip of it at the base of the existing wall above ground level to improve the risk of rising damp not being able to escape outside?]]>