Mike

Turns out they have: Yates T. (2002). Final report on the construction of the hemp houses at Haverhill, Suffolk, client report 209-717 Rev2, BRE, Watford, 2002. I don't have a copy, but the CAT mention key findings in a report: https://www.votehemp.com/wp-content/uploads/2018/09/building_with_hemp_and_lime.pdf Short version - two houses were built, sponsored by the Suffolk Housing Society in collaboration with BRE, who performed a full assessment. Despite having higher U-values (Hemp homes 0.58 w/m2.K Control Homes 0.35 w/m2/k) they performed as well as the standard construction, occupied or unoccupied. This may be partly explained by hempcrete's 'thermal mass', low thermal bridging & airtightness.

I visited the CAT, but when it was regarded as a strange hippy commune and eco-anything was generally treated as a joke. So long before the WISE building was built. I must get back there some day. Depending on the time of year: Compare the Climate and Weather in Lille and Winchester - Weather Spark The LGCgE is a University - or, rather, a collaboration by 4 regional universities - so it's already been extensively tested 'for real'. You may not have too long to wait. IndiNature are already producing & selling UK hemp-based insulation (though not yet hempcrete blocks) and have applied for their first BBA certificate.

Ideally stick to one of the models independently tested for the Passivhaus Institute: https://database.passivehouse.com/en/components/list/ventilation_small. The 'efficiency ratio' is the overall measure, taking into account heat recovery + electricity consumption. Passivhaus certified units come with a more realistic measure of their performance compared to non-certified units (Paul have a short explanation).

I hate to say it, but seems more like hopium than a solution. Is there any proper research as to the long term performance. Yes. The French Réhafutur 1 research project (http://www.rehafutur.fr/) was the initial research project, a collaboration between the housing association Maisons et Cités and the University of Artois, with support from the regional Eco-business Creation and Development Association (CD2E), the French Building Federation, the Federation of Construction Employers Cooperatives, and others. It's 60 miles inland from Calais, south of Lille, so a similar climate to southern UK. The 4 elevations were insulated with different materials: 300mm hempcrete blocks in thin-bed lime mortar, with the gap against the brick wall filled with hemp fibre (so functionally similar to the in-situ hempcrete linked to above) 350mm blown-in cellulose fibre 350mm flax wool 360mm sheep wool There's some brief info here in English - https://www.isohemp.com/en/hemp-solution-heritage-renovation and a video of the insulation here in French: https://www.youtube.com/watch?v=QkR4WATzp0Q The building was monitored by the regional Civil Engineering & géo-Environnement Laboratory (LGCgE) using 80 probes, measuring temperature & heat flow (on the internal surfaces, external surfaces, and boundary between insulation and structure of the external envelope), temperature & hygrometery (in the centre of the insulation), ventilation air flow & internal air quality. Energy use was logged and the external weather measured. Various metrics were calculated including actual -v- predicted U-values, thermal inertia and thermal decoupling; plus acoustic performance, materials wastage, embodied energy, cost effectiveness, environmental life cycle analysis, etc. The outcome of this (and a subsequent pilot) was that the hempcrete was judged the optimal solution for wall insulation. As a result an initial 50 houses were insulated with hempcrete in Pecquencourt a couple of years ago (to be increased to 115), with a plan to expand that to 1,000 by around 2026, and eventually more as the local production capacity and knowledge are developed. There's some info on these plans in English here: https://batinfo.com/en/actuality/le-bailleur-maisonscites-lance-lexperimentation-pecquenchanvre_19931 and a video in French here: https://www.youtube.com/watch?v=7u8gxdJP_pU

In a traditional building that is subject to some moisture, one option I'd consider is adding hempcrete to the inner face of the wall, improving the U-value and maintaining breathability without isolating the interior from the 'thermal mass' of the wall. There's an example here: https://lowcarbonbuildings.wordpress.com/2019/09/15/a-domestic-insulation-project-chapter-3-weeks-of-weetabix-walls/

An interesting project. Consider installing MVHR (Mechanical Ventilation with Heat Recovery) too.

And here's a photo:

There is no hope for energy reduction when people fit that many lights It does depend on the room size, but the power used by a dozen 3W LED lamps is not huge, while often being preferable (visually and in energy use) to a ceiling full of 10 or 12 Watt LED downlighters.

So you can switch them all from the door simultaneously (or wherever the light switches are), instead of individually. Not a problem if you only have a couple of lamps, but if you have 6 or 12 of them scattered around a room, it's much easier.

These and sockets are still available and I use them for lighting controlled by wall switches (hard wired ones!!,!,) Me too - very useful for that, though better to use a sleeved version. Domestically the corresponding shuttered BS 546 sockets are still permitted for lighting. I wish they had an equivalent in France, where instead the best you can do is to add 2 regular power sockets (confusing) or flex connection plates (annoying) to a lighting circuit. Problem is, there's USB-C and there's USB-C Most laptops, phones etc benefit from >5V for faster charging, but most cheap chargers, inc all those I'm aware of built into UK sockets, will only give 5V Yes, I can recommend USP PD (Power Delivery) power supplies to save space when travelling, if you have a compatible device. They have USB-C plugs on the cables but can go up to 48V.

The changes in socket types are why I choose only regular 230V power outlets.

A load-shedder (such as the Hager 60060) may be a way around this, temporarily cutting the supply to a number of selected circuits if the total load approaches the maximum.

Yes, that looks right.

Vermiculite and Perlite both absorb water, so I wouldn't use them.

To check, they should have published the AEV ratings - see https://fr.wikipedia.org/wiki/Technique_des_portes_et_fenêtres#Classement_AEV

I'd be choosing sand-cement too.

In the UK it's normal to have the double glazed unit on the outside and the sliding secondary window inside, but that's no-doubt because UK windows are normally outward opening. Not the only way. In Europe I seen a full double window used. That is, an inward opening double-glazed window internally, and an outward opening double-glazed window externally - which worked very well, acoustically. If using a sliding window externally, check that the weather sealing will be adequate. I've not come across that as a recommendation and it wouldn't be the case in the normal UK situation. The air is going to be transmitting most of the sound, so IMO it's not necessary.

Think I'll stick to these

From the ventilation aspect, provided you make provision to do 2 later, you could try 1 to start with and see how it goes. However from the fire control perspective it may be advisable / you may be required to have a ceiling, which is what I'd do anyway.

A very useful clarification, and if the aircon can handle the excess heat that's also very good. I'd say that was much less of a concern than with a separate external extract. The MVHR's extract fan will need to work a little harder as the air flow through extract vent in the cabinet goes into reverse & more has to be pulled through the other extract vents, but a Zehnder is doubtless clever enough to adjust for that automatically. I agree :)

That ticks off everything I mentioned above. So most likely a major part of the solution is to replace the extractor fan, boost the room temperature, and leave the eves cupboard doors open. And apply some mould killer. It seems unlikely that the damp is coming through the roof (if that's what you're thinking the damp proofing would help), so probably not. But maybe I've misunderstood. As you're sure it's all built OK as above, I don't think that's likely to help.

Good question! It may be useful in the heating season (not necessarily, if the building is already heated enough), but the problem is handling it. The heat's generated in a confined space, which will rapidly heat up. As per the calculation above, I reckon that would mean extracting in the region of 161m³/hr of air from that one cabinet. Maybe the MVHR could add that much extract in boost mode, but that would boost extract from all over the house, which would tend to push up heat loss overall, while not extracting anything like enough from that one cabinet. So it becomes complicated...

If it's a breathable membrane installed in accordance with the manufacturer's recommendations / the BBA certificate, and the conversion was done to Building Regulations standards, then the probability of that being the source of the problem is low. More likely it's a problem generated within the house. Condensation is caused when warm humid air cools down, which suggests that you need to improve ventilation in the room / house, remove or reduce the sources of humidity, improve the heating in the room, or all of these. As the problem is only in this room, maybe that's because it's not much used and therefore may has a shut door and maybe isn't heated often / much? At least I'd guess that the eves cupboards are the least heated / worst ventilated part of the room.

I believe the formula for the required airflow in m³/hr = Watts x 3600 seconds / ((maximum permitted °C - ambient °C) x density of air (kg/m³) x specific heat capacity of air (J/kg.°C) So taking 40°C as the maximum (a reasonable limit), and ambient as 22°C, then 1000W x 3600s / ((40°C - 22°C) x 1.225 kg/m³ x 1012 J/kg.°C) = 161m³/hr. Which is about 95CFM. So, to answer your question, yes if we ignore heat waves when the ambient temperature may go well above 22°C. There are no doubt other options, but the Shelly EM with a suitable clamp around the cable could be used to monitor the energy use. It also has an integrated 2A 230V relay that could be used to control a valve, though you / your electrician would need to study the manuals. Not yet used it myself, but I'm thinking of doing so to automatically switch on a kitchen hood if the hob or oven is switched on, though not sure when I'll get around to that. I wouldn't expect a problem with recirculating, as the MVHR remains in balance, but this is external extract. However it would be interesting to get the thoughts of someone who ignored the normal advice and installed a kitchen hood with external extract (though they probably wouldn't run it for as long as a movie).