Hello from London

[SteamyTea]

24 minutes ago, Iceverge said:

I couldn't find it on the ICE database

https://drive.google.com/drive/folders/1vHpIGkpgkplmItn_0IaPXQ-5Fxnr08Wz

 

That is the link to the University of Bath download.

 

And it is Craig Jones, not Steve Jones.

[AdamJ]

12 hours ago, ZacP said:

Not wishing to throw another complication into the mix @AdamJ but have you discovered/considered woodcrete ICF? Products such as durisol, istotex etc? Rather then being made of eps they use recycled chipped timber. This might help sequester carbon in the fabric? I don’t know much about it, but the thought crossed my mind! 
Good luck!

 

5 hours ago, NickK said:

 

@Iceverge I am rubbish at this sort of stuff so won't even attempt to work it out myself so here it goes....how much would this be reduced by if you went down the isotex/durisol route? Thanks

 

Thanks for the suggestions ZacP and NickK.

 

I hadn't thought about either of those products.  I will have a look at them and make a similar comparison to the other systems.  I also had a look at the ICE database and woodcret (or waste wood chips, the main ingredient) is not on there. The different wood products have quite different carbon footprints depending on how processed they are, so I wouldn't want to take a guess.  We could follow @SteamyTea 's suggestion and contact Dr Craig Jones and Professor Geoffrey Hammond - the ICE database points to the Circular Ecology contact page: Contact Circular Ecology - Circular Ecology. 

 

If I can get the info on woodcrete and cellulose (the ICE database doesn't include figures on this) then I can do similar embodied carbon sums to the ones I have done for SIPS and EPS ICF for Durisol and the twin wall timber frame versions of the house. 

 

I've started back at work today so won't have as much time to run the numbers as I did over the Xmas break, at least until the weekend. 

 

 

Edited January 4, 2021 by AdamJ
spelling

[NickK]

6 hours ago, ZacP said:

Great minds @NickK!

Sorry I completely missed your post at first but genuinely interested for myself. Really like to idea of ICF and woodcrete types just make you feel somewhat ‘green’ whilst building it. 

[DavidO]

On 31/12/2020 at 16:44, AdamJ said:

Are there timber frame suppliers that you or Buildhub members recommend?  

Turner Timber Frames, based in Hull but have nationwide coverage, did a fantastic job for us. They are timber engineers really rather than just frame builders. First class product. First class service (both technical and practical). And a fair price.
 

One of the most important aspects of self building, which is too often overlooked when wrestling with the technological challenges, is choosing the “right” people to work with. From the architect (if you use one) right down to the brickie’s labourer, it makes such a difference. We count ourselves very fortunate to have worked (mostly) with good tradesmen and suppliers, and some of them were great, a pleasure to work with. Turner’s were up there among the best of them.

[Ferdinand]

Was that one post?

Consider me awed. 

[AdamJ]

13 hours ago, DavidO said:

Turner Timber Frames, based in Hull but have nationwide coverage, did a fantastic job for us. They are timber engineers really rather than just frame builders. First class product. First class service (both technical and practical). And a fair price.
 

One of the most important aspects of self building, which is too often overlooked when wrestling with the technological challenges, is choosing the “right” people to work with. From the architect (if you use one) right down to the brickie’s labourer, it makes such a difference. We count ourselves very fortunate to have worked (mostly) with good tradesmen and suppliers, and some of them were great, a pleasure to work with. Turner’s were up there among the best of them.

Thanks for the tip on Turner Timber frames.  It looks like their Super Advanced system would be the equivalent to the buildups I've been looking at, as they include an additional internal layer of PIR to overcome thermal bridging. 

 

I've written to Durisol to ask for embodied carbon data.  Isotex publish some in their EPD, but not for all their blocks, and not their higher performing blocks (see page 13 of EPD-Wood-cement-blocks-for-wall-systems-Isotex.pdf (blocchiisotex.com)) I've written to them for more information as well.  I also asked them to clarify the difference between their 2D and 3D U-values - I assume the 3D value includes the effect of thermal bridging, but I'm not sure.  

 

Given the way I'm expanding this exercise to cover more systems, I think I also ought to include the more typical UK construction (masonry cavity wall) for comparison! 

[Gus Potter]

1 hour ago, AdamJ said:

Thanks for the tip on Turner Timber frames.  It looks like their Super Advanced system would be the equivalent to the buildups I've been looking at, as they include an additional internal layer of PIR to overcome thermal bridging. 

 

I've written to Durisol to ask for embodied carbon data.  Isotex publish some in their EPD, but not for all their blocks, and not their higher performing blocks (see page 13 of EPD-Wood-cement-blocks-for-wall-systems-Isotex.pdf (blocchiisotex.com)) I've written to them for more information as well.  I also asked them to clarify the difference between their 2D and 3D U-values - I assume the 3D value includes the effect of thermal bridging, but I'm not sure.  

 

Given the way I'm expanding this exercise to cover more systems, I think I also ought to include the more typical UK construction (masonry cavity wall) for comparison! 

Just a thought.

 

Embodied carbon is one measure.

 

AdamJ. Yes.. to make the best job of reducing your carbon foot print starts on the drawing board as you are doing.

 

At some point you need to often dig a hole in the ground, cart muck away. Then you often need to pour some concrete, the sand/ aggregate requires transportation to the concrete plant, the cement takes a lot of energy to make it. You need to cart muck away and so on. You purchase PIR insulation.. oil based product, maybe concrete tiles, hard to avoid. Then at the end of the day the building has to some extent a limited life so someone has to dispose of all this and that carbon cost may well exceed the saving you may make during the lifespan of the building. Ideally you want to leave the site "just as you found it"

 

It's fine crushing up an old block of concrete flats for recycled aggregate, but if you then cart the stuff fifty miles or more and sit with the wagon engine running in a traffic jamb / unload it on site / the operatives come to work in van to do this and so on then it kind of defeats the purpose?

 

As an aside and ask..  look at how many houses are getting knocked down at the moment partly to do with the VAT system.

 

Ideally and one expression, is to "walk softly and leave no footprint" that is what your house should do. So my view is that if you are carbon aware you may want to think about what you are leaving behind you and not just reducing your footprint when you are living in the house.

 

Once you start to think about this then you can start to look at your basic structure. Take an ICF basement. That is often a big hole, lots of concrete and lots of oil based insulation product.. I'm not convinced that your air source heat pump etc will offset the overall carbon cost and the subsequent disposal cost.. or do we want to leave that disposal issue for the next generation to solve? yes you may save a bit on electricity during your occupancy and so on.

 

I think that if you really want to make an impact then it's worth looking at the project in the whole, the carbon cost of construction.. fuel for wagons, concrete, insulation and so on. Then the carbon savings when you are living in the house, then the reduction in your carbon footprint at the end of life stage.

 

When you weigh all this up you may find that you can save some money while also leaving significantly less of a carbon foot print overall. If you look at it this way then you may be able to afford carbon wise the extra odd luxury while making a positive contribution to the environment. 

 

Although this may sound cynical I have written this in the hope that BH members that want to self build with a limited budget, while doing the best for the environment may be encouraged to look at the whole of life carbon cost. It is not always necessary to buy the "latest" and usually expensive technology when you can skin the cat in another way.

 

Self building can be a great journey, often folk move on, you can see it on BH.. lots of serial renovators and repeat self builders etc!

 

 

 

 

 

 

Edited January 6, 2021 by Gus Potter
clarification

[keith65]

Hi 

If we look at this we should go back and live in yurts as there impact would be small. All building uses transport for materials its like changing coal fired power stations to burn wood then import the wood from Canada?. We all need to build as responsible as posable, we could all live in something smaller with less bathrooms etc but this is a choice we all make.

 

Self building can be a statement in many ways, it is need verses want/like and the environment its a balancing act and hard to get right !

[SteamyTea]

I think ICE shows the basic manufacturing energy/carbon costs and the delivered costs on many of the products.

Generally, transport is a very low cost, though a very visible one.

 

Also, we pull down very few houses, I think a house built today will still be about, on average, in 500 years (read it somewhere, years ago)

[Ferdinand]

@AdamJ

 

Can I just do a spot detail check on your argument - I'm following along, but not in total detail?

 

You say:

 

On 31/12/2020 at 02:29, AdamJ said:

 

Floor area is approx 180-190 sqm GIA depending on wall thickness.  

 

And you are talking about annual heating demands of 320-350 kWh.

 

As I make it, that is about 10x smaller than the passive house standard, which is 15 kWh per sqm per year, or 3000 kWh approx on that size of house.

 

Is that what you intend?

 

Cheers

 

Ferdinand

 

[AdamJ]

20 hours ago, Gus Potter said:

Just a thought.

 

Embodied carbon is one measure.

 

AdamJ. Yes.. to make the best job of reducing your carbon foot print starts on the drawing board as you are doing.

 

At some point you need to often dig a hole in the ground, cart muck away. Then you often need to pour some concrete, the sand/ aggregate requires transportation to the concrete plant, the cement takes a lot of energy to make it. You need to cart muck away and so on. You purchase PIR insulation.. oil based product, maybe concrete tiles, hard to avoid. Then at the end of the day the building has to some extent a limited life so someone has to dispose of all this and that carbon cost may well exceed the saving you may make during the lifespan of the building. Ideally you want to leave the site "just as you found it"

 

It's fine crushing up an old block of concrete flats for recycled aggregate, but if you then cart the stuff fifty miles or more and sit with the wagon engine running in a traffic jamb / unload it on site / the operatives come to work in van to do this and so on then it kind of defeats the purpose?

 

As an aside and ask..  look at how many houses are getting knocked down at the moment partly to do with the VAT system.

 

Ideally and one expression, is to "walk softly and leave no footprint" that is what your house should do. So my view is that if you are carbon aware you may want to think about what you are leaving behind you and not just reducing your footprint when you are living in the house.

 

Once you start to think about this then you can start to look at your basic structure. Take an ICF basement. That is often a big hole, lots of concrete and lots of oil based insulation product.. I'm not convinced that your air source heat pump etc will offset the overall carbon cost and the subsequent disposal cost.. or do we want to leave that disposal issue for the next generation to solve? yes you may save a bit on electricity during your occupancy and so on.

 

I think that if you really want to make an impact then it's worth looking at the project in the whole, the carbon cost of construction.. fuel for wagons, concrete, insulation and so on. Then the carbon savings when you are living in the house, then the reduction in your carbon footprint at the end of life stage.

 

When you weigh all this up you may find that you can save some money while also leaving significantly less of a carbon foot print overall. If you look at it this way then you may be able to afford carbon wise the extra odd luxury while making a positive contribution to the environment. 

 

Although this may sound cynical I have written this in the hope that BH members that want to self build with a limited budget, while doing the best for the environment may be encouraged to look at the whole of life carbon cost. It is not always necessary to buy the "latest" and usually expensive technology when you can skin the cat in another way.

 

Self building can be a great journey, often folk move on, you can see it on BH.. lots of serial renovators and repeat self builders etc!

 

 

 

 

 

 

Thanks Gus, I take your point that a whole life assessment including transport and disposal would be better. I agree, though I don't know yet how to factor those two additions in easily.  

 

As SteamyTea said, the ICE database does include some transport emissions. The authors say the database has a "cradle to (factory) gate" scope, covering modules A1 to A3 in the EN 15978 standard.  A1 Is the extraction of the raw materials, A2 is the transport to the manufacturing site, and A3 is manufacturing.   To be more comprehensive, I should then add in transport from the manufacturing location to my site, and energy I use on site in building with those products.  I'd want to have a rough idea on how large a proportion transport-to-site emissions are before putting a lot of time in comparing so many different systems. 

 

I don't have any idea how to estimate the end of life emissions!  I do know that the a lot of the neighbouring buildings to my site were built around 1880-1890, and then another lot around 1960, so are between 60 and 130 years old.  I hope my house lasts at least as long (longer because it will be such a good house!  )  I would love to believe that SteamyTea's 500 year statistic will apply to my house.   Even if it only lasts 60 years, the decision on how to dispose of the house at at the end of its life will likely fall to someone else, but I could design it so the parts could be easily re-used.  If I was designing it for re-use, though, I might be looking at using steel beams and columns and pre-cast concrete planks, because these are most easily re-used in new construction projects, from what I understand.  Again, before embarking on a comparison between end-of-life emissions on multiple systems I would want to find out what sort of proportion of the whole they make up.  Can you give me a rough idea? 

 

13 hours ago, Ferdinand said:

@AdamJ

 

Can I just do a spot detail check on your argument - I'm following along, but not in total detail?

 

You say:

 

 

And you are talking about annual heating demands of 320-350 kWh.

 

As I make it, that is about 10x smaller than the passive house standard, which is 15 kWh per sqm per year, or 3000 kWh approx on that size of house.

 

Is that what you intend?

 

Cheers

 

Ferdinand

 

 

Hi Ferdinand,

 

My headline goal was net-zero carbon in-use. I also want the house to be comfortable, and then beyond that to consider embodied carbon when making the decision on construction method.  I don't mind if I don't follow the passive house standards to get there, but it does seem likely that I will end up doing much the same things that a passive house would.  Maybe after all of these discussions I will have come to a different conclusion on what my goal ought to be. 

 

The 320-350kWh energy use figures I reported from the Designbuilder simulation are the 'fuel consumption' totals for heating, which I think is different from heating demand in the passive house standard.  The figure I'm quoting is (I think) equivalent to the figure on the electricity meter (if the meter gave me a breakdown of where the energy is spent), which takes into account the efficiency of the ASHP. I assumed a COP of 3, so each unit of electrical energy is giving me 3 units of heating energy.  The passive house 15 kWh per square metre target is for heating demand, which doesn't take into account the efficiency of how the heat is delivered, just how much heat is needed.   I think the equivalent figure in the design builder simulation might be the total of the figures for heating and heat recovery from the 'system loads'. For my simulated ICF house that is 755 kWh heating delivered by the ASHP and 459kWh 'free' heating from the MVHR, which would suggest the demand was 1214kWh.  I'm just learning my way around this so could have things wrong - someone more familiar with passive house or designbuilder please correct me. 

 

I've also put my simulated heating set point at 17 degrees, because I personally would find that a comfortable minimum. (I also had a look at the Arup comfort tool to back up my own assumptions: Arup Advanced Comfort Tool) I think the passive house assessment has it at 20 degrees.  If I change my simulation to have a 20 degree heating setpoint the heating demand goes up to 6000kWh and the 'fuel consumption' energy use for heating goes up to 1600 kWh. 

 

Because I'm interested in net-zero carbon, the figure I focused on was the energy use total, rather than the demand.

 

On the embodied carbon front, someone from Durisol wrote back to me and copied in a manager who may be able to answer the question - if I get the figures I'll post them here because it seems a few people are interested in how woodcrete type products compare. 

[Gus Potter]

Hi Adam.

@AdamJ

 

Thanks Gus, I take your point that a whole life assessment including transport and disposal would be better. I agree, though I don't know yet how to factor those two additions in easily.  

 

As SteamyTea said, the ICE database does include some transport emissions. The authors say the database has a "cradle to (factory) gate" scope, covering modules A1 to A3 in the EN 15978 standard.  A1 Is the extraction of the raw materials, A2 is the transport to the manufacturing site, and A3 is manufacturing.   To be more comprehensive, I should then add in transport from the manufacturing location to my site, and energy I use on site in building with those products.  I'd want to have a rough idea on how large a proportion transport-to-site emissions are before putting a lot of time in comparing so many different systems. 

 

I don't have any idea how to estimate the end of life emissions!  I do know that the a lot of the neighbouring buildings to my site were built around 1880-1890, and then another lot around 1960, so are between 60 and 130 years old.  I hope my house lasts at least as long (longer because it will be such a good house!  )  I would love to believe that SteamyTea's 500 year statistic will apply to my house.   Even if it only lasts 60 years, the decision on how to dispose of the house at at the end of its life will likely fall to someone else, but I could design it so the parts could be easily re-used.  If I was designing it for re-use, though, I might be looking at using steel beams and columns and pre-cast concrete planks, because these are most easily re-used in new construction projects, from what I understand.  Again, before embarking on a comparison between end-of-life emissions on multiple systems I would want to find out what sort of proportion of the whole they make up.  Can you give me a rough idea? 

 

Adam I think you are doing a sterling job here exploring this complex issue.

 

You asked "..Again, before embarking on a comparison between end-of-life emissions on multiple systems I would want to find out what sort of proportion of the whole they make up.  Can you give me a rough idea? " I wish I could!

 

A bit off topic..life span of your house. For all, when the loadings are calculated for your house they are based on the probability of occurrence. Take the wind loading, (an environmental load) here we often base this on a return period of 50 years and design for that and when you apply for a mortgage the lender works on a similar probability to ensure their asset is protected. However, we know  that timber framed buildings last a lot longer than that, hundreds of years, often it's fire that ends their life. I can't see for example how a modern timber framed house cannot also last well beyond the " design life" if it is well maintained.

 

Turning back to fact that I can't answer your question! Modelling is often an intrinsic part of modern development and the build process. Structural Engineering has benefitted from this, the computer models are significantly more advance even compared with 5 or 10 years ago and this continues as the processing power of computers grows at an exponential rate. But as we know predicting the future and how the materials we use now can be recycled later is difficult to say the least.

 

This uncertainty can throw any model right off. Also, these modern models generate a huge amount of data that needs to be stored.. and that uses electricity, I try and avoid thinking about how much electricity data storage requires. The energy requirement for this may well increase as we start to gather real time data on home automation for example. But at the moment this is one cost of innovation and this will pay dividends in the future.

 

As an aside. A colleague who works in the oil and gas industry recounts hearsay where they were analysing the all up loads / stresses on a rig using FE analysis. The output was a bit on the red side and they felt that as the client was not an Engineer they may have a concern as there was a lot of red on the model. Someone joking said, just change the colour palate on the graphics... the same can apply to the carbon model.

 

At the back of my mind when I was posting on this was.. What if you are on a limited budget, first time self builder say but want to do the best for the environment. We know that for example the latest technology.. some batteries, circuit boards, complex systems often have rare earth metals in their construction. It's reported that there is growing activity relating to mining of the seas for these elements and we intrinsically know that this is probably not good for the planet.

 

To be clear, I'm certainly not suggesting that we should abandon innovation. But if you are on a budget maybe select the materials that we already know are not too bad for the environment.. sheep's wool insulation, straw as a good example, although timber , steel etc  are already proven to be easily recovered and recycled.

 

Lastly another way you can also protect the environment is to spend the time getting the quality of your build up to scratch, good detailing and workmanship to keep the weather out and so on. A well slated roof can last for over a hundered years if properly done, a bad one much less. I do wonder when you see the complaints that are raised against new build how much of a carbon cost is attaching to shoddy building practices and workmanship.

 

Keep posting AdamJ and thanks again for sharing.

 

 

 

 

 

 

 

 

[AdamJ]

Hi Guys, 

 

Update to my comparison of different methods. I have now looked at the performance of a more typical Part-L compliant masonry cavity wall as a baseline comparison, a full fill masonry cavity wall to the same 0.15 max U-value I was targeting for the other systems, and a solid masonry wall (using hollow concrete blocks) with external insulation, which to me seems the best way to do a cheap but high performance masonry wall (though it is the thickest wall so far). 

 

I've also looked at the embodied carbon of the twin-wall timber frame with cellulose insulation (its the lowest so far), and the 'perfect wall' timber frame with external GPS insulation.  I did manage to find the embodied carbon of the fire retardant, the acrylic render and also low-carbon basalt reinforcement as an alternative to steel.  

 

I still have to look at the embodied carbon of all the masonry systems, and I haven't looked at a woodcrete ICF system yet for either performance or embodied carbon, so there are still gaps.  I also want to separate out the embodied carbon and sequestered carbon in the timber, so that both are shown in the table, rather than just the net negative figure.  I'm interested in how the embodied carbon of the masonry options compare. 

 

Energy use wise, there really isn't that much in it - even the 'standard' notional Part L compliant system isn't that bad (but it does have the same SIPS roof, high performance windows and a heat pump like all the others - its just the walls that have changed) though I imagine real world performance will be worse because of the difficulty of achieving the targeted performance with traditional masonry cavity wall construction. I've been doing Passive House 'bite size' training over the last couple of weeks (4 x half days) and seen a lot of photos of shoddy masonry walls with big gaps between insulation boards etc. I've also been told a lot about the difficulties of getting a timber frame airtight with an internal membrane due to internal junctions, which makes me think it will be easier to get good airtightness from the 'perfect wall' set up because its an external wrap with far fewer penetrations.  

 

	Typical Masonry Notional Part-L (GPS Insulation)		Masony Cavity Full FIlled (Rockwool Insulation)		Masonry External Insulation (GPS Insulation)
Wall performance	(worse air infiltration assumed)
Wall thickness	439	mm	463	mm	490	mm
Un-usable wall thickness	439	mm	463	mm	490	mm
U-value	0.2	W/m2K	0.15	W/m2K	0.15	W/m2K
U-value (nominal, not including bridging)	0.18	W/m2K
Phase shift	11	hours	18	hours	13	hours
Thermal capacity inside	218	kJ/m2K	256	kJ/m2K	299	kJ/m2K
Simulation energy in use
Annual energy used for heating - current climate	534	kWh	252	kWh	244	kWh
Annual energy used for cooling - current climate	113	kWh	70	kWh	60	kWh
Energy load for heating - winter design day	3.4	kW	2.5	kW	2.5	kW
Overheating hours (assuming no cooling) - current climate	123	hours	96	hours	82	hours
Annual energy used for heating - 2080 forecast climate	173	kWh	162	kWh	157	kWh
Annual energy used for cooling - 2080 forecast climate	2337	kWh	1798	kWh	1677	kWh
Hot summer day cooling energy - 2080 forecast climate	21.1	kWh	15.85	kWh	14.8	kWh
PV array spec to deal with 2080 cooling	6	kWp	4	kWp	4	kWp
Carbon produced with grid electricity for heating/cooling 2020	151.4	kgCO2e	75.3	kgCO2e	71.1	kgCO2e
Carbon produced with grid electricity for heating/cooling 2080	251	kgCO2e	196	kgCO2e	183.4	kgCO2e
Carbon produced over 60 year period	10815.9	kgCO2e	7656.4	kgCO2e	7175.9	kgCO2e

 

	ICF		ICF + Timber floors		SIPS		TF: Twin wall + Cellulose		TF: Perfect wall + GPS
Wall performance
Wall thickness	373	mm			275	mm	395	mm	416	mm
Un-usable wall thickness	373	mm			275	mm	395	mm	268	mm
U-value	0.15	W/m2K			0.15	W/m2K	0.14	W/m2K	0.14	W/m2K
U-value (nominal, not including bridging)
Phase shift	non relevant				9.5	hours	14	hours	6.3	hours
Thermal capacity inside	328	kJ/m2K			28	kJ/m2K	36	kJ/m2K	35	kJ/m2K
Simulation energy in use
Annual energy used for heating - current climate	320	kWh	261	kWh	350	kWh	315	kWh	350	kWh
Annual energy used for cooling - current climate	12	kWh	52.9	kWh	148	kWh	117	kWh	145	kWh
Energy load for heating - winter design day	2.8	kW	2.76	kW	2.65	kW	2.4	kW	2.6	kW
Overheating hours (assuming no cooling) - current climate	58	hours	74.5	hours	144	hours	139.5	hours	142.5	hours
Annual energy used for heating - 2080 forecast climate	183	kWh	176	kWh	175	kWh	159	kWh	169	kWh
Annual energy used for cooling - 2080 forecast climate	1629	kWh	1713	kWh	2440	kWh	2142	kWh	2405	kWh
Hot summer day cooling energy - 2080 forecast climate	14.6	kWh	15.3	kWh	21.6	kWh	19.7	kWh	21.3	kWh
PV array spec to deal with 2080 cooling	4	kWp	4	kWp	6	kWp	5	kWp	6	kWp
Carbon produced with grid electricity for heating/cooling 2020	77.7	kgCO2e			116.5	kgCO2e	101.1	kgCO2e	115.8	kgCO2e
Carbon produced with grid electricity for heating/cooling 2080	184.1	kgCO2e			261.5	kgCO2e	230.1	kgCO2e	257.4	kgCO2e
Carbon produced over 60 year period	7318	kgCO2e			10509.7	kgCO2e	9221.1	kgCO2e	10365.7	kgCO2e
Embodied
	ICF				SIPS		Twin wall		Perfect wall + GPS
Concrete (using Cemfree)	4251.5	kgCO2e			575.9	kgCO2e	575.9	kgCO2e	575.9	kgCO2e
Basalt reinforcement	498	kgCO2e			54.1	kgCO2e	54.1	kgCO2e	54.1	kgCO2e
EPS insulation	5308	kgCO2e			759.5	kgCO2e	759.5	kgCO2e	5370.8	kgCO2e
Growing medium	60	kgCO2e			60	kgCO2e	60	kgCO2e	60	kgCO2e
EPDM	489.5	kgCO2e			489.5	kgCO2e	489.5	kgCO2e	489.5	kgCO2e
Bituminous Membrane									8.6	kgCO2e
PIR/PUR Insulation (Internal board)	426.9	kgCO2e			1904.5	kgCO2e	426.9	kgCO2e	426.9	kgCO2e
PIR/PUR Insulation (SIPS Core)	1912.6	kgCO2e			8532.3	kgCO2e	1912.6	kgCO2e	1912.6	kgCO2e
Mineral wool insulation					128.4	kgCO2e	128.4	kgCO2e	128.4	kgCO2e
Resilient layer floor insulation					73.4	kgCO2e	73.4	kgCO2e	73.4	kgCO2e
Cellulose insulation							910	kgCO2e		kgCO2e
Screedboard floor					1003.2	kgCO2e	1003.2	kgCO2e	1003.2	kgCO2e
Fire retardant	66.4	kgCO2e			258.9	kgCO2e	258.9	kgCO2e	258.9	kgCO2e
Acrylic render	1837.9	kgCO2e							1837.9	kgCO2e
Airtight coating in Twinwall - unknown at this point
Total embodied	14850.8	kgCO2e			13839.7	kgCO2e	6652.4	kgCO2e	12200.2	kgCO2e
Plywood	-1804.9	kgCO2e
OSB	-1748.2	kgCO2e			-10947.4	kgCO2e	-6980.9	kgCO2e	-7720.4	kgCO2e
Timber planks (external walls)									-2941.4	kgCO2e
Timber stud (external walls)							-3004	kgCO2e	-1351.6	kgCO2e
Timber studs (internal walls)	-650.5	kgCO2e			-2063.9	kgCO2e	-2063.9	kgCO2e	-2063.9	kgCO2e
Timber battens (service void)	-8	kgCO2e			-424.9	kgCO2e	-79.7	kgCO2e	-79.7	kgCO2e
Timber battens (rainscreen)					-469.7	kgCO2e	-469.7	kgCO2e
Timber floor I-joists					-507.6	kgCO2e	-507.6	kgCO2e	-507.6	kgCO2e
Timber siding					-1703.8	kgCO2e	-1703.8	kgCO2e
Total sequestered	-4211.6	kgCO2e			-16117.3	kgCO2e	-14809.6	kgCO2e	-14664.6	kgCO2e
Net embodied	10639.2	kgCO2e			-2277.6	kgCO2e	-8157.2	kgCO2e	-2464.4	kgCO2e

 

 

[Iceverge]

Tremendous work.

 

Did you include the sequestered energy for cellulose?

 

How are you calculating overheating? I used PHPP and it was much less sensitive to construction methods. 

 

Keep it up. 

Edited January 18, 2021 by Iceverge
Mistake

[oldkettle]

Am I right that the external finish you have included for your sips/tf is just wooden cladding? If that's the case will it actually last as long as the rest of the house? You will certainly need to paint it regularly. 

[Adsibob]

On 29/12/2020 at 22:54, AdamJ said:

Hi Buildhub, 

 

Given that I've been thinking about self-building for years, I'm amazed that I haven't noticed this forum before now.  It seems like a really active and friendly place, with a lot of knowledgeable members. 

 

I've got an option on a site in south-east London (which took a lot of searching and negotiating to get), and now that I have the option my second step is figuring out what construction method to use. 

 

My goal with this house is for it to be net zero carbon, and to begin with I'm trying to do a comparison between ICFs and SIPs. I know that any construction method can be used to create a high performance, energy efficient building fabric, but both of these methods have a reputation for achieving good performance levels relatively 'easily'. 

 

I'm doing some simulations of energy in use (using a trial of Designbuilder I downloaded last week) and calculations of embodied carbon (in an Excel spreadsheet, using the ICE database) to get an idea of whether the higher embodied carbon of the concrete could be justified with lower energy in-use.  I'd love to share these with you guys and get your thoughts when they are done. What is the best sub-forum to post in? New House and Self Build Design? 

@AdamJ welcome to the community. 
I’m curious to learn how you found your plot; I looked in London for over a year and then gave up.

[AdamJ]

On 18/01/2021 at 08:46, Iceverge said:

Tremendous work.

 

Did you include the sequestered energy for cellulose?

 

How are you calculating overheating? I used PHPP and it was much less sensitive to construction methods. 

 

Keep it up. 

Hi Iceverge, 

 

For the items that aren't in the ICE database, I've had to look elsewhere for information. A lot of products have an EPD which includes A1-A3 data, but they don't separate out the embodied and sequestered carbon in the way that the ICE DB does for timber.  For the cellulose, I used this EPD from Soprema (Conventional Loose-Fill Cellulose Insulation - Transparency Catalog (soprema.ca)), where they mention sequestration of carbon but don't give a separate negative figure. I assume that the figure they give is 'net' and does take it into account.   

 

All my 'in use' figures come from the Designbuilder simulations, which is based on Energy Plus.  I'm no expert, but I understand that PHPP does not perform a dynamic simulation, so the two pieces of software must be using different methods behind the scenes to get their results.   To make things easier for myself I didn't use the version of the model that I modified with smaller windows and brise soleil, so I know the overheating is worse than it could be, but hopefully it is a fair comparison of the different build-ups. In the current climate the variation between the build-ups doesn't seem very large, its only in the more extreme future scenario that they start to look more different from one another. 

 

On 19/01/2021 at 19:43, oldkettle said:

Am I right that the external finish you have included for your sips/tf is just wooden cladding? If that's the case will it actually last as long as the rest of the house? You will certainly need to paint it regularly. 

 

Hi oldkettle. Yes I just assumed wooden cladding for those option. I hadn't thought too much about finishing and maintenance, but you're right it would probably need to be painted.  I grew up in a painted wooden house so that doesn't seem too bad to me!  An intriguing option is acetylated timber like Accoya, which is supposed to be much more durable that typical softwood cladding (it has a 50 year warranty).  I think the process will increase the carbon footprint compared to standard wood, and the price.  I could probably find out the carbon footprint for comparison's sake. 

 

On 19/01/2021 at 19:59, Adsibob said:

@AdamJ welcome to the community. 
I’m curious to learn how you found your plot; I looked in London for over a year and then gave up.

Hi Adsibob, thanks for the welcome.  

 

I started out looking at auction catalogues and plots that were put up for sale on Rightmove, but decided that after a while that was a dead end.  There was almost always something really wrong with the plots that were actually up for sale that, to the extent that a lot of them border on scams.  They description always says something like 'potential for development subject to obtaining the necessary consents', and then I would dig into it and find out the site is actually only accessible from a private road, and the owner of that road refused to give permission (or something equally bad).  I came to the conclusion that the good sites never made it to the open market - the agent would offer it up to a local builder or developer they knew who would snap it up - so only the total duds were actually listed for sale.  

 

I just started walking or cycling around, and taking pictures of spots that looked like they had potential. When I got home I would look up the owner on the land registry and search for any planning application that might have already been made on the site.  If it looked promising I would write to the owner at the address given on the land registry. Mostly nobody wrote back. Sometimes people would write back, but not because they wanted to sell.  Eventually one wrote back to say they were interested in hearing my offer, and that was the start of the negotiation.  I think it took 70+ sites before I got that positive response.