Cheaper ways to heat a log cabin workshop (UK)
Hello good and clever people of Tildes, I need some advice.
With electricity the price it is, and my wife having a sizable workshop in the garden, I'm looking for ways to bring down the heating cost.
Her workshop is 5m x 4m x 2.2m, and the wood is 44cm thick. It's a chunky beast. She makes gifts and personalised items, so when she has the heatpresses and mug/tumbler press on the go, it gets toasty. If the sun comes out, also toasty. However, over night, it gets super chilled, almost to whatever temp is outside. To combat this I decided to use a Govee Electric Space Heater, 1500W with Thermostat, WiFi & Bluetooth. However, this barely does anything and the electric usage flies up.
What are good options here? The office is about 10 metres from my house. It's too far to extend the home central heating via plumbing, plus too much lagging. I don't want to spend a fortune, so any sensible options I'm willing to entertain. If we're talking a couple of thousand, it's off the menu.
Thanks for any help.
Dropping an edit with a link to the actual cabin: https://www.tigersheds.com/product/the-gamma-44mm-log-cabin/
It's not like a USA style log cabin, that's for sure!
Edit 2: Okay - wall insulation looks like the next thing to tackle before even thinking about heating it. Thanks folks.
Looking at the setup, I can see a few issues that need addressing. The main problem is that 44mm thick wood walls provide very minimal insulation - you're essentially heating the outdoors at this point.
Here's what I'd suggest, in order of priority:
Insulation first - This needs to be addressed before any heating solution will be effective. But it is a shed...
For heating, I'd recommend looking into Chinese diesel heaters. These are essentially knockoffs of Eberspächer heaters but much more affordable. They:
If you want a more conventional solution, a mini-split heat pump would be your next best option
Your current electric heater is probably the least cost-effective solution - you're fighting physics trying to heat an poorly insulated space with resistance heating in UK electricity prices.
Whatever you decide to do, I very strongly recommend insulating the shed.
I will echo the need for insulation. You're fighting a losing battle without it.
Also, I do not know if it's available across the pond, but DIY install mini-split heat pumps are commonly available in the US which would certainly save on the installation costs.
Are you trying to keep the contents of the workshop warm or make it more comfortable for a person inside the room? I'm assuming the latter so would recommend getting something that puts out radiant heat and placing it near where she is going to be working. I'm thinking an overhead radiant heater would probably work best for a workshop (these are more commonly advertised for use outside on a verandah or BBQ area), even the heat lamp style ones aimed at bathroom usage would help.
There are a variety of indoor use infrared panels on the market as well. Often advertised for at home workers behind their desk.
Ambient warmth of 12c for over night to stop mould growth on clothing would be good.
During the days and evenings when she is working, a sensible 21c would be ideal.
I like the idea of an over head style one used to heat outdoor heating areas. They kick out some serious warmth. I wonder if they do thermostatic and controllable ones. The only ones I've seen have been heat settings for 1/2/3 and that you have to manually turn off yourself. Time to look at those.
Do note that these do not increase the ambient temperature much. Radiant heaters are intended to heat people up not the area.
How often is this occupied at night? To me this screams woodstove. Old school is cheaper but you have to tend to it more, newer is pricier, but it’s less messy, may be able to run pellets, and can run on a timer and will have automatic startup.
And if you go the route of wood stove, and come across a sturdy camping wood stove at a decent price, make sure it has a standard sized chimney pipe. I bought one for ~$150 last year with the intent of heating my 10x12ft shed/office and it's literally impossible to find pipe, bends, and adapters to go through the wall/roof for its size.
I did a ton of research into how viable it would be to heat my shed with one and everything looked good, but I goofed up and didn't know anything about stove pipe size standards.
Overnight, never. Working hours here are daylight and early evenings. Near Christmas, she'll finish up about 10pm.
For the nighttime warmth, it's more about ambient to stop her clothing getting damn and mouldy.
This site says it’s okay to let the fire die slowly overnight.
At least in the U.S., you can get new traditional wood stoves for $350 and used for a less. Don’t know what the cost of wood is in the U.K., but it wouldn’t be dependent on electricity. Y’all would have to start the fire and get it going while she’s working, so that might be a downside.
Considering you mention it is a log cabin I would guess that there is space between the logs. Meaning that the cabin is very well ventilated but not very isolated.
You don't want to completely remove ventilation (bad for your health, moisture, etc) but at the very least have it be on your terms.
Can you provide pictures? It might be as easy as reducing gaps between logs/panels.
I have updated my original post with a comment, but it is not the USA style of real log, more the Swiss manufactured type: https://www.tigersheds.com/product/the-gamma-44mm-log-cabin/
It is well ventilated as she has an electric exhaust fan if required. Generally this is used when she needs to do sublimation work as it can get quite chemically smelling.
I was more hoping you would have pictures of the actual thing. Specifically the seems between the timber and such.
Looking at the pictures you provided it does seem to be light on insolation anyway. So whatever you do for heating I feel that improving isolation is going to be needed or you will keep facing high costs for continuous heating against heat loss.
You're facing one-time expenses (such as insulating the cabin sufficiently to reduce ongoing heating costs), or on-going expenses (energy for heat, whether it's fuel or electric or sun).
I can't really think of any cheap way that doesn't involve getting something free though. Like, if you knew a contractor or construction person or something, who could give you free/cheap insulation and help install it, that would be cheap. If you knew a carpenter or someone who worked for a local shop that regularly has a dumpster full of wood off-cuts you'd be allowed to regularly show up and take for a wood-burning stove, that'd be free (or cheap).
Most ongoing "free" solutions probably involve time (and resources like vehicle use along with loading/unloading). You might live next to an unclaimed forest, but logging or collecting deadfall would take hours each week to find and prepare and load into a wood fired stove. That's not "free" even if it wouldn't cost direct dollars to obtain, for example.
Perhaps get some solar panels, hook them straight up to an electric heater? That's "free" after the one-time capital cost. During the day whatever power the panels can throw down to the cabin is "free heat" at that point. Doesn't help at night, obviously, and batteries are very expensive. The solar panels themselves are typically very affordable, if you can avoid having to pay through the nose to an electrician to wire them into the structure's electric panel. It's installation and the battery that break the bank on solar often times.
Wind generator, same as the solar panels, for when the winter wind is howling? Do you live by a creek or river, could get a hydro generator, same concept.
But free or cheap that actually provides heat ... tall order.
Solar is possible, but the weather in the UK means low level generation - not enough to power a decent heater, I would imagine.
The floor and ceiling are wrapped in Therma Wrap Insulation, but the walls are not. Also, the doors and windows are double glazed, but obviously let through a lot of cold regardless.
Cheap is what I'm aiming for, not free. I was just after ideas. I've looked at electric oil filled radiators, fan heaters, and halogen space heaters. Unfortunately, I'm not a man of good maths for best heating / room size / cost per Watt with these things, and I was hoping someone in here just said "Ah, you want X because of Y, and it'll be cheaper than what you have now." Long shot, but Tildes seems to hold a lot of very bright people.
Electric heating basically all costs the same. It's all 100% efficient. Every watt in turns into a watt out, eventually. To get more than 100% - which is possible - you need a heat pump, and they're not the cheapest. See my comment below.
Themawrap is better than nothing, but only just. You really want insulation board, as thick as you can afford/have space for. You can, at a push, tape and skim this board with plaster to create a "wall" but it's quite a long way from best practice! A layer of thin plasterboard over the top would be the minimum workable solution, I'd say. Screw a few battens to the wall, drop the boards in, screw down the plasterboard over the top, tape and skim, paint and you're done. If I am making that sound easy, it's because it kinda is. Measure twice, cut once and it's not that hard. Skim coating is moderately fiddly but the rest is simple.
If you don't already have a cavity wall, insulating is a tricky and/or expensive job. But it is worth it. My workshop is next to my wife's office and isn't insulated - despite being (single skin) block walls, the thermal gradient is basically a cliff. Heat just vanishes out of there. Her office gets warm and stays warm, even overnight when there's no heating happening and outside is cold. In the winter the amount of time I can work for is limited by how long it takes for my fingers/feet to get too cold to bear. Nextdoor she's just sitting there toasty warm chatting on Zoom (OK, OK, I know she's working really)
If you have an MKM Building Supplies local to you, they are often the best value for things like plaster and insulation board, and they'll usually deliver free (because shifting full size boards is a nightmare if you don't have a van).
You'll probably also want something to insulate the walls as well. Something like this may be good (my dad's used similar to insulate his shed that doubles as his workshop), though I imagine you'll also want another boarding layer to cover it to keep the space looking nice?
In addition to insulating the walls, these insulation film kits make a big difference on the windows. It's best to put them on the face frame so they make a thicker barrier of enclosed air. Try to get them stuck down as straight and taut as possible, then tighten them up with a hair dryer. They come in all kinds of sizes including big enough for the big window in the door.
I know you said your windows are double pane, but these will still help, especially if they are operable because this also seals all the air that leaks in tiny gaps around the panes.
Not sure if this is really up your alley, but I’ve been intrigued by a listing I saw on the French leboncoin.fr for large quantities of sheep’s wool. It was insanely cheap. It made me want to come up with a project to justify buying it. What I came up with was insulating, which is quite a common thing to do with wool. Unfortunately I don’t have a property to insulate, but you might want to look into it. It could be a cheap, and above all fun, project to do. Source the wool locally, figure out a way to get a layer of the stuff on the inside and get it done!
My wife's office is fairly similar. I insulted the hell out of it (and because it is quite small, it was affordable to do with fancy wool insulation rather than rockwool, which helps the R-value), made sure all the windows and the door had good seals, then installed the smallest heat pump I could find, which was about £600 and provides 3KW of heat for about 600W input power, although because it's well over spec for the volume of office, it rarely runs at full power. It's also very efficient at heating the space, rather than the 2KW fan heater she had before, I think largely because it's mounted high on one wall and circulates air more effectively. I estimate the heat pump paid for itself in the first winter. Bonus, it can also be used for AC during the summer, at which point it's free to run because our solar array is kicking out plenty of power then.
The only issue I had was she kept leaving the office and forgetting to turn the heat pump off, which did get a bit pricey running overnight or worse, over an entire weekend. So I installed a wife detecting radar and a few Home Assistant rules and now it turns itself off fifteen minutes after she's left. This investment has already paid for itself too. (next, fit smart switches to the lights so they do the same, but the payback on turning off a few LEDs is rather longer!)
Oh, it is technically illegal to install your own heat pump. So you might prefer to get the commissioning done by an F-Gas certified engineer. Luckily my neighbour is one of those and he did it for a couple of beers. But it's an easy (and safe) enough job to do yourself, just don't tell anyone...
One note on using a natural fiber like wool as insulation, you need to be very mindful that water (including condensation from the air) can't accumulate inside the cavity. Not my area of expertise, but I'd be surprised if you can't find guidance on moisture management in insulation with a bit of searching. Mold is always a risk in walls even with synthetic insulation, but I think you have to be extra careful with natural fibers that they stay dry and can dry out if they do get moist. I suspect with u/g33kphr33k's wife being the only occupant the internal moisture sources are pretty low at least, but my understanding is the UK is pretty humid so something to consider all the same.
Getting unnatural fibres damp isn't great either! Ideally you want a one-way vapour barrier between the insulation and the outside so the moisture can leave and not enter. Also airflow, drainage and so on. Wood is pretty good though because it does breathe, so that's a plus. A small dehumidifier can help a lot too.
Right now it's about 97% RH in my garden. That's pretty normal for winter.