On Dec 17, 11:42*pm, robgraham wrote:
js - I take it that what you are saying is that a single brick, 75mm
stud wall with OSB facing is going to have the same insulation value
as a single brick wall with no lining at all ?

No, it will be better, just nothing like as good as with insulation.

You NEED to check the following R values, grabbed off Google.

Uninsulated Brick + Cavity + OSB..
- Single brick - R = 0.12
- Unventilated Cavity - R = 0.18
- 18mm Plywood - R = 0.70
- Combined R = 0.12+0.18+0.70 = 1.00
- Effective U = 1/R = 1/1 = 1.0

Four wall surface area = 4x 3 x 2.3 = 27.6m^2
- U value of uninsulated wall = 1.0
- Internal temperature = 21oC
- Heat Loss = Area * U * 21 = 27.6*1*21 = 579 Watts


Insulated Brick + 50mm Celotex + OSB...
- Single brick - R = 0.12
- 50mm Celotex - R = 2.63
- 18mm Plywood - R = 0.70
- Combined R = 0.12+2.63+0.70 = 3.45
- Effective U = 1/R = 1/3.45 = 0.29

Four wall surface area = 4x 3 x 2.3 = 27.6m^2
- U value of insulated wall = 0.29
- Internal temperature = 21oC
- Heat Loss = Area * U * 21 = 27.6*0.29*21 = 168 Watts


Assume perfectly insulated floor, ceiling & windows.
- Uninsulated - 579W = 7p/hr cost
- Insulated - 168W = 2p/hr cost

Assume 100 day winter, 2hrs/day
- Uninsulated = £14 cost
- Uninsulated = £4 cost

Assume 100 day winter, 8hrs/day
- Uninsulated = £64 cost
- Uninsulated = £16 cost

The reality is uninsulated will not have perfectly insulated floor,
ceiling & windows.
- 2hrs/day becomes £42 v £12
- 8hrs/day becomes £192 v £48

Additionally, overnight heating re frost & condensation may be
required.
- It is here that uninsulated becomes a money pit
- You are background heating for 22/16hrs a day which adds up


One other comment re insulation on the inside:
- Insulation on the inside = fast warm up, no thermal mass
- Insulation on the outside = slow warm up, high thermal mass

For a workshop insulation on the inside is probably best.
- Background heating - tube heater on Smiths Plug-In Thermostat
- Boost heating - wall mounted FX20VL fan heater (thermostat), floor
industrial jobbie etc

That way it gets warm very quickly indeed.