Ventilation/Condensation/Heat options for this old barn?

[Mark Lewis]

I have an old barn near my house that I am going to use as a gym and workshop. So it needs heating (but not much...doesn't ever need to be cosy!) and more important - ventilating. Condensation in there with lots of metal sports/tools stuff will be very bad.

It's a mix of the original stone and lime mortar walls, a concrete floor and modern insulation and boarding under the roof. It also has various spots where concrete has been used for repairs over the years. Despite this rather inappropriate use of materials, it is rock solid and bone dry everywhere. I have spent the day with a lime expert learning how to fill in any large voids with stone and a hot lime mortar, then finish with a lime slurry and a lime whitewash. So the walls are going to look pretty good and finished in appropriate materials real soon.

Given the floor and roof are solid and dry, they are being left as they are (and covered with rubber flooring) oh, it also has modern UPVC doors amd non-opening (no vents) windows. As such, it is going to be a fairly well insulated (for a very old barn) building and that is going to create humidity and condensation problems, especially as a gym!

So what is the solution to keep the air inside fresh and dry and heat the place?

With very little knowledge of the subject, I am thinking either...... an air-conditioning unit which should address everything or a MVHR unit and separate heating? or something else?? PIV??

Any thoughts?

[Lesgrandepotato]

Barns tend to have blow through ventilation from the little slot windows. I’d embrace that and pop a log burner in.

Let it work like it was designed to work

[Mark Lewis]

Lesgrandepotato said:

Barns tend to have blow through ventilation from the little slot windows. I’d embrace that and pop a log burner in.

Let it work like it was designed to work

This has no ventilation at all - no slot windows. And a log burner is not really going to maintain a low, background, temp thats acceptable for workshop and gym.

[Snow and Rocks]

Maintaining any heat in there with bare stone walls is going to need a lot of energy - I think trying to keep it heated 24/7 might be unrealistic.

A woodburner with it's continuous draw of air would solve both the ventilation and be able to belt out enough heat for sporadic heating but I appreciate is probably a bit of a PITA for a gym.

PIV not a bad shout otherwise to keep things fresh.

Edited by Snow and Rocks on Friday 27th December 11:00

[OutInTheShed]

Snow and Rocks said:

Maintaining any heat in there with bare stone walls is going to need a lot of energy - I think trying to keep it heated 24/7 might be unrealistic.

OTOH, massive stone walls store a lot of heat.
So the temperature changes less than outdoors day/night.

so, with breathable walls and a low-ish level of ventilation, avoiding condensation might not be too difficult?

Buildings are not all the same, local climates are not all the same and people have varying goals and varying standards of needing to achieve those goals exactly or vaguely.

The simplest and traditional way to keep an old building dry is to heat it.
Sometimes a dehumidifier is the best answer, sometimes a blend of the two approaches.

Insulating the roof better may help. By reducing the temperature swings.

Dealing with any source of water, leaks, rising damp, rain soaked walls etc etc can be key.

[ewanjp]

MVHR (i'd assume decentralised) is only going to be worth while if there is heat to recover. If it's a gym then I'd assume it won't be in use 24/7 so keeping a big fat stone building warm is going to cost a lot. Once you're into the cardio you'll generate your own heat I guess, so maybe just work on the ventilation (humidity triggered extraction fan of appropriate scale) and maybe so of those infrared heater lights so you're heating the people rather than the space and only when you need to - works well in the climbing place I go to (effectively a large unheated barn).

Fan of the channel btw!

[Snow and Rocks]

A big kerosene powered industrial space heater would work if there's a sensible route for the flue and is probably a much more economical solution than trying to keep the place continously warm.

[Mark Lewis]

ewanjp said:

MVHR (i'd assume decentralised) is only going to be worth while if there is heat to recover. If it's a gym then I'd assume it won't be in use 24/7 so keeping a big fat stone building warm is going to cost a lot. Once you're into the cardio you'll generate your own heat I guess, so maybe just work on the ventilation (humidity triggered extraction fan of appropriate scale) and maybe so of those infrared heater lights so you're heating the people rather than the space and only when you need to - works well in the climbing place I go to (effectively a large unheated barn).

Fan of the channel btw!

Thanks.

Is extraction going to be enough - just drawing air out? No need to dehumidify or AC the air instead (as well)?

[ewanjp]

Mark Lewis said:

Thanks.

Is extraction going to be enough - just drawing air out? No need to dehumidify or AC the air instead (as well)?

Well the air outside if likely going to be cold, so will not have that much water in it even at 99% (relative) humidity. The hole you'd need to make in the wall is probably the same size (or could be with a reducer) as the one you'd need for the DMHVR, so given an extractor fan is cheap, could just try it and swap it over if it doesn't work. You are really trying to reduce condensation, which means removing the cold surfaces that the air will condense on - i.e. the outside walls, that is tricky given i'm assuming you want to keep the nice stone walls visible.

[AJLintern]

If you're only going to be in there now and then, and want to feel some warmth fairly quickly, then one of those cheap Chinese diesel heaters could be a good option. Because they heat the air directly and can be ducted to where you need it, you start to feel some heat within minutes. I've got one as a temporary heat source in my garage project to make it possible to work in there during the cold months. Can be quite toasty and cheap to run.
(needs to be set up with the exhaust venting externally though - mine is outside in a cabinet with the inlet/outlet air ducted through the wall)