Matt Wardman

Cheers. I'll take the advice, and start another thread in a few days. In the meantime, thanks to everyone who has commented on my posts - most enjoyable. And best wishes to anybody bobbing up and down or stranded at the end of a flooded pontoon because of all the extra water.

Can I ask for some help - what do I call the various spaces in a narrow boat, wider boat etc? This is for if I create some sort of power consumption spreadsheet model at the end. In a house I would be talking about Kitchen, Living Room 1, Living Room 2, Study, Hall, Downstairs Bath, Bed 1, Bed 2, Bed 3, Upstairs Bath and so on. Is there a list which covers the various spaces in a canal/river boat. I am thinking perhaps Galley, Saloon, Cabin 1, Cabin 2, Cabin 3 (in a long, wide barge?), Bath/Shower, Corridor (or perhaps Circulation Space). I could just do Room 1 -> Room n, but it is perhaps better to get it roughly right if that is straightforward. (I have some think-posts still to do on a few aspects, but TBH I'm not up to thinking on January 2nd so I'm doing something easier 🙃). All comments are most welcome.

Agree that's important, and I probably put it under careful planning, homework and sweating the design detail. Incorporation of units into the space needs thought. For a narrowboat, one thought could be for a type of "not full MVHR" as I have used effectively in renovations of older houses. I think an airflow from one end to the other end is fairly clearly the option for a narrowboat (though from the middle to both ends is another possibility). I would perhaps put an extractor unit (probably 12V Supply Heat Recovery) in the kitchen end, so that food smells go out rather than permeate into the bedrooms etc, then an input unit at the other end. Wrinkles could be a filter on the input - possibly activated carbon to keep the smells from other narrowboats out, humidistat or timer control of one or both units, and possibly an on/off switchable heater (say 300W) on the input unit to give an option for a low heat when required at certain times of the year or to warm up the boat a little in the morning or at bedtime. Through room flow could be facilitated either by door gaps (ie shave the top or bottom of the inside doors) or via soundproofed inter-room vents. For a full MVHR and a narrowboat sized space I think 100mm or rectangular 110mmx54mm ducting would be suitable.

For a through the wall unit like that the standard install is to incline the hole in the wall slightly so that any condensation runs outward and drips off the end. I go a little further and put a section of soil pipe set in the wall projecting slightly away from the surface on the outside 1) to protect the fabric and surface of the wall just in case any moisture does manage to condense on the pipe, and 2) so that the unit can be taken completely out from the inside to be maintained or replaced. It leaves a tiny gap between the unit and the piece of pipe which can be siliconed.

I think there's something in that, and also that there are many different types of heat exchanger (eg 'counter flow, concurrent flow, cross flow and hybrids of those types such as cross counter flow and multipass' *). I think here be a rabbit hole, which probably ends at an Appendix in an ISO or British Standards document. I expect that there will be approved methods of making such calculations, which allow comparisons, and approved ways of doing measurements under standard conditions. And that in practice we will find a benefit, but just *how* big the benefit is will depend on other aspects of our environment, such as (for example) just how good the air seals are around our window frames. eg if only 80% of the air from our living space exiting via the MVHR system, then the system will work efficiently on air it gets at, but leakage elsewhere will degrade performance of the overall system which includes all the leaks. * I can see how those concepts are all different categories, but I got the words from here: https://www.thermopedia.com/content/832/ ======================== Bah humbug the autosec merged my comments. MVHR in Houses and Efficiency etc. On MVHR, here is a recentish shortish 2020 Passivehaus Trust paper on MVHR for anyone wanting to pursue the subject a little further. They emphasise that in their analysis such systems deliver a desirable living environment in addition to energy saving. My personal anecdote on this is that if I am in a very high humidity environment I start coughing. We need to keep in mind that a) PHT are authoritative but also advocates and b) That applying insights from house to boat and vice-versa needs care. This paper has shown that previous analyses indicating that MVHR systems should only be installed in properties with an air permeability of 3 m³/m².hour @50Pa or less are based on outdated information and flawed assumptions using a modelling system which was never intended to be used to compare ventilation systems. A modern MVHR system will result in significantly lower CO2 emissions at any reasonable level of air permeability. However, an MVHR system’s primary function is ventilation and, in this capacity, it is far more effective at providing a good quality indoor air environment – regardless of external conditions – than natural ventilation. There is no clear up-to-date evidence behind the rule of thumb that says MVHR is inappropriate for dwellings with air permeability above 3m³/m².hour @50Pa. This analysis has shown that MVHR systems result in improved ventilation and lower carbon emissions for all levels of airtightness. There is a compelling case for MVHR systems to be fitted in all new dwellings and to be strongly encouraged in retrofits where significant reductions in energy demand are being targeted. https://passivhaustrust.org.uk/UserFiles/File/research papers/MVHR/2020.04.27-The Case for MVHR-v7 new cover.pdf

To comment on these numbers. According to me (I did some approx. calculations using a heat /ventilation model right near the top of the thread) a narrowboat interior is approximately 2m x 2m x 12m = 48 cubic m, which is 48,000 litres. So for one air change per hour (ach) via ventilation (for a lowish level of ventilation), we need 48,000 litres / 3600 seconds, which is 13.33 litres per second. So 10 l/s gives 0.75 ach, or the 6l/s of the low-trickle setting (High trickle = 9l/s, Boost = 15l /s) on the Heat Recovery extractor fan I have mentioned elsewhere on thread gives 0.45 ach. Both seem to me to be not unreasonable rates of ventilation to keep a living space comfortably fresh, and are not much different from eg figures in the Building Regs. I would quote a number from the Boat Safety Scheme, but they have not yet considered mechanical ventilation afaics. I'll definitely say that both God and the Devil are in the Details *, as always. Of course other factors apply - such as a boat being opened up in the day, and closed down to help warm it up at meal times or autumn evenings, but when closed down I'd say that such ventilation is a reasonable level of throughput. And types of appliance such as solid fuel burners etc being often present, and the need to consider Carbon Monoxide and Carbon Dioxide. I'd argue that as NBs are smaller spaces with a KitKat-like form factor where the floor is below the entry level, probably a higher level of ventilation in terms of ach than a normal house would be appropriate. Matt W * With apologies to Mies van der Rohe, who left the Devil out of his aphorism. The post I referenced:

Since I started the conversation about specifics of MVHR within the thread (I think) let me add my thruppence-worth. I think I have been quoting 75-80% of heat recovery from outgoing air into incoming air. My specific citation is for a Heat Recovery fan (ie a through the wall fan with a heat exchanger in the pipe); I have been using the Vent-Axia Lo Carbon Tempra units for about 8-9 years now, and they quote 'up to 78%' (link to manufacturers data). Interest points for this type of product is that they often have 12V versions available (as in the link, and I presume to allow immediate use in bathrooms), they use very little power (in this case 2W in trickle mode -> 20W on boost) ,and can be managed by thermostat or humidistat. (BTW imo perhaps don't put a HR extractor fan in a shower room, since the incoming air is *always* slightly cooler than the air already in the room, so your beloved-coming-out-of-the-shower will be subjected to an airflow that feels cold, on top of the perceived cold caused by water evaporation from skin, and you may receive the appropriately vigorous customer feedback.) I've put out a request on BuildHub to see if anyone has any info on MVHR efficiency, which I normally see quoted as "in the range 60% to 95%". How far it applies to all the ventilation air in your dwelling or boat depends on how effectively you have air sealed the unit so that all the ventilation goes through the HR system. There is a decent background article on these systems, and the hows, whys and wherefores, here: https://www.homebuilding.co.uk/advice/mvhr-the-beginners-guide It's worth noting that MVHR also delivers benefits in a more controlled environment, with eg a better humidity level of perhaps 50-55% rather than fluctuations between 50% and 80% if gas cookers, or other naked flame appliances which generate water vapour as part of their process. Lower humidity can also save money since there is less water in the air to be heated up. In a narrowboat setting doors are perhaps opened and closed more (but perhaps not when one is ensconced in the evening or cooler seasons), so ability to adjust temperature relatively quickly with little energy and 'thermal inertia' is a factor. Can I thank @Willonaboat for putting forward his thoughts about his own live project, which are very valuable 'feedstock' data for us to reflect on - as is real data which tends to argue either side. Much appreciated. It's all about learning and finding better ways for us to meet our own goals, whatever they are.

All you need now is the other 47 marginal gains.

Half length as well, so a quarter. The Bugsy Malone narrowboat ! https://www.youtube.com/watch?v=rYeJn24ZDh8 On the finances, don't electric propulsion NBs already get 25% off the licence - which is several hundred a year ie a marginal gain 🙂?

It's an interesting thought with respect to implicit assumptions. Do wheelchair users, or women (average height in UK 5'5" = 1.624m), or ethnicities who have a shorter stature, need a 1.9->2m ceiling height in narrowboats? Why do we British Men think we are entitled to it, and it has to be everywhere? 🤠 🤠 🤠 🤠

As I read it the OP was meaning "usable by us as we get older", rather than 'accessible' in the sense defined by the Equality Act. I think that there quite hard limits for accessibility in a narrowboat for a wheelchair user depending on the precise type of mobility impairment that that person experiences, though remember that wheelchair users are under 10% of disabled people. I make it ~1.8% wheelchair users and ~20% of the population with a disability by Government definition. For example, everybody with Diabetes Type I is counted as disabled, as the condition is likely to have a long-term impact on health and wellbeing, but short -> medium consequences do not usually have a major impact if the condition is managed well. Things like working locks under the English lock-yourself-through model are very difficult, unlike Scotland where "you don't go through on your own, McGubbin" is in place (aiui).

I'm chipping away at getting to a hopefully useful model for some of those numbers in a week or so's time (without defining the duration of "or so".) Do you have approximate numbers for how many air changes per hour your ventilation generates, and the environment you create eg in terms of relative humidity and how much it varies? (I think one can get at an approximate estimate of the former by comparing actual "fixed ventilation" to the theoretical CRT requirement, and the latter if you have a min/max thermometer / hygrometer.)

I think a conversation around the basic mechanisms of humidity and temperature control used for narrowboats and houses would be useful. A traditional narrowboat - like a traditional house - is ventilated (when doors etc are closed)by holes which have been cut in the walls, and gaps around doors and air leakage around penetrations. In winter, or at other times, we may stuff the holes with cloths or similar if we want to create a fug. In NBs it is "fixed vents" (ie holes) mandated by the CRT (10000sqmm is according to me approximately the same as a 110mm - 4.5" - hole). In houses it is traditionally chimneys and air bricks both sides to ensure a cross-flow air current under the floor, which disperses moisture and tries to make the internal climate the same as the outside climate by coming up through the floor. Add in gaps around doors and windows and pipe penetrations etc. AFAICS the Boat Safety Scheme does not define how much ventilation in terms of airflow but in terms of the size of the hole required in your boat, but does define resilience to eg CO by suggesting 2 air changes per hour (ach). Plus the requirements for "low/high" ventilation (which makes some sense around eg accumulation of CO2 in the bottom of the boat interior). In their more recent form for houses, holes have become "trickle vents" installed in window frames, plus all the other forms of leakage. In this sense buildings and boats 'breathe' as air and moisture move in and out. For houses the more recent trend is to keep air changes to a lowish minimum, and require ventilation to meet certain standards, around ideas such as extract ventilation (ie background), purge ventilation to remove smells, pollutants etc rapid - all to create a safe / comfortable environment. Building Regs define houses as "less airtight" or "more airtight". The former is approximately "traditional", the latter is moving towards 'passive', which means putting an airtight membrane around the entire house inside the walls, and controlling the airflows rather than allowing leaks. When a new house is built, an air leakage test is a requirement, which means closing all the windows, and using a "blower door" to see how much air escapes at 50 Pascals pressure. * Doing 'passive' well requires meticulous attention to detail, and you don't find out how well you did it until the end. To boil that down and relate it to this thread, if we used "fixed vents" then there is a continual stream of air that we have paid to warm up escaping. When mechanical ventilation is applied that means that heat energy escaping in airflows can be recovered to heat incoming air as we can extract through a heat exchanger, with an efficiency of 80%+, rather than a continual loss of heat *with* the escaping air. That is a potential quite large energy saving, but it depends on questions around when is heating used, will we accept a different philosophy for creating a comfortable living space (and is it possible on an NB), and the form of heating used. I'll have a crack at some numbers later. How much of a marginal gain it is, and what else that would require of us are imo useful questions when thinking about LENBs (Low Energy Narrow Boats). I think there are some possible lessons to learn here, especially from techniques used to reduce energy bills in older houses when renovating - but as ever it's only some of the stuff that can be transferred, perhaps with modification. (*) https://www.designingbuildings.co.uk/wiki/Air_permeability_testing

Thanks for the reply. I think the point about weight is interesting - especially on a thread for Low Energy Narrow Boats as afaics there are relatively few ways to reduce required propulsion energy. In my head these seem to be reducing weight (and therefore draft / blocking ratio a little, but with stability implications), more streamlined or less draggy hulls, power train efficiency (from the motor to the propeller), and potentially reducing speed (a challenge when starting from an upper limit of 3mph). A BMW i3 only weighs 1.385 tonnes and is relatively light - correct, but that is still double the weight of the first 4 seat hatchback I owned, which weighed 685kg, and the i3 battery is relatively small. Moving up the size range, electric SUVs are headed towards 3 tonnes, and even a mid-size BEV Estate such as the MG5 is around 2 tonnes with a claimed range of ~200 miles. My own full size diesel estate (Skoda Superb) is about 15% lighter than this. An area deserving of more attention than it gets imo, especially as these can often go faster than most drivers (including me) are used to, and higher weight is linearly more energy to be dissipated in a collision which increases the consequences of error. But I went a bit off topic for the thread, and have a number of areas relating to domestic energy consumption on an NB I am still reflecting on before offering an opinion - ventilation, windows, incidental heat gains and losses, and peak load for a few.

I find EVs interesting in that they are being sold on just one aspect of the problem - replace fossil fuel cars and their emissions by clean electricity. EVs are inefficient - they are perhaps 50% or more heavier than necessary, and can accelerate so fast that large numbers of drivers (including probably me) are no skilled or experienced enough to handle the 0-60 in 5-6 seconds sprint appropropriately. Any crazy numbers of them are electric SUVs which are less safe for everyone not inside the SUV, but when the justifying reason happens, such as 'but it might snow', they slide off the road in confusion. Yet EVs are also in some ways a very inefficient solution. They still clog up our roads with traffic, while a real answer would make alternatives practical and safe in the UK - whether e-scooters, cycles, mobility scooters, micro cars such as Smart of Citroen AMI, or just walking. On current trends we will have EVs racing up and down our narrow lanes making them just as dangerous as Fossil Fuel vehicles do. Someone who lives in a village and loses their driving licence through sight-deterioration with age will be just as stuck as they are now. That's an interesting stat, perhaps suggesting that there are many thousands of boaters who can carry a large overhead without needing to worry about it. It must be quite pricey to keep a boat in a marina for 95-99% of the year without using it, and paying all the licences etc. BTW Happy Christmas everyone. Good point. I think for canals (especially adjacent mooring locations) a problem I see with water source is impact on the temperature of the canal, which could be quite marked. Because canals are quite restricted waterways compared to the amount of boat, especially on sections with adjacent moorings. I had not really internalised how tight canal channels are until I did some consultation with cyclists who had ended up in canals when I was thinking about the safety aspects of tow-path cycling with clipped in pedals. Of the many cyclists who had ended up in canals, overwhelmingly they could stand up to recover. Ballpark numbers are that a water source heat pump may need several cubic m of water every hour. Three or four boats moored together running WSHPs may have a material impact on the slow flowing water in a canal - perhaps dropping the temperature by a couple of degrees(?). So I would look more to air source.