Cold Walls

We live in a besser block home with no insulation in walls. Ceiling has some kind of blow in fluff insulation. During winter, two rooms out the back of house which get very little direct sunlight are very cold. Rooms are about 3x3m in size. Looking at cost effective ways to make these rooms not so icy cold. Ive done diy double glazing on one of the rooms and that stopped condensation but the walls obviously are ice cold. I am wondering if thermal curtains hung along the walls would work, trapping the cold between the walls and the curtain. I understand i could look at injection insulation but its not something my wallet can handle atm. Both rooms have 1kw convection heaters and they do warm the rooms up but if rooms are kept closed, once they get cold and walls are cold, i believe it takes do long to warm up as the walls are so cold and they are cooling the air in the room, hence my idea of thermal curtains on the walls. Im open to suggestions. Btw we live in Tasmania.

My experience is that heating mass is much better than heating air, because once you stop heating the air, the temperature of the mass takes over, which I think you have found. Given insulation is currently beyond budget, it looks like you're looking for a cheap temporary (or permanent) solution.

A couple of questions:

1. Is there anything cladding the concrete blocks on the inside?
1a. If so, what is it?
1b. If so, is there a gap between the cladding and the blocks?
1c. If not, what is the transition between the block wall and the ceiling, floor, window and doors (cornice, architrave, skirting, etc)?

2. Are the blocks in the wall filled or hollow?
2a. If hollow, are the tops of the walls accessible?

3. Are the cold walls on the southern side of the house?
3a. If so, are they getting sun at any time?
3b. If not, what is stopping the sun from shining on those walls (vegetation, pergolas, eaves, proximate buildings, etc)?

No cladding. Blocks are hollow and would be accessible from roof but youd have to lift some iron to gain access. Theres render on outside but other than that just the block wall which the rooms are on. Naturally skirting near floors but its just hollow blocks with nothing more thsn paint/render.

That wall is south facing and in winter gets basically no sun. Nothing can be done to change that. Sun is so low in sky that theres no sun or very limited to early morning or late afternoon.

To me and as you said its clearly the mass of that south wall which is the problem. It gets cold and stays cold coz rooms are kept closed. Lounge has a wood fire and master bedroom is north facing so it is nowhere near as cold despite the same block designed wall as it gets sun all day.

I was thinking some kind of internal wall/structure that goes over the block wall. This could be filled insulation etc. Downside is the rooms would lose space with the added wall. I considered curtains on the walls to see if it helped block the cold. During spring etc the rooms are fine. Enough sun to make the walls not icy cold.

Given there is no internal cladding, I asked about cornices, architraves and skirtings because I wondered whether you could add a lining without having to change all those transitional elements. Unfortunately, it sound like you can't. The good news, with hollow blocks you will be able to blow insulation into the wall at a later time when you can afford it - but insulation is only part of the story.

The problem you have is that in order for thermal mass to work in your favour, you need to get heat into the mass, which will dissipate back into the room later. As the walls get no sun, the only way to introduce heat is from your heating inside the house. You said you have the doors to these rooms closed, but perhaps you should consider opening them to get some heat into the rooms, and thus into the walls. If you do that, you will not want to line the inside of the walls, as then you will be working against your intentions. However, you might consider insulating the outside of the wall by attaching an external wall board, which may or may not be cheaper that the in-wall insulation - or even batts behind a false wall of painted plywood.

If any of that is still too expensive, then you might want to isolate the chill from the inside of the walls by covering them as you have suggested, but perhaps with hanging rugs (think tapestries) or perhaps even fixing carpet to the walls. You might be able to find some secondhand that would work.



BTW, if the walls are getting sun in the morning and afternoon, that suggest the eaves or something else could be getting in the way; but of course, changing eave coverage is a serious undertaking. That said, anything can be manipulated. For example, if you had a bit of room, you could use secondhand mirrors, shiny steel, or even white painted board to redirect some light (and thus heat) onto those walls.