Heating Fabric of building

[Murph1603]

Hi Guy’s, just wondered what was everyone’s opinion on initial heating of a new build and heating the fabric of the build and the drying out I.e will the moisture absorb more heat until dried out as such 

[saveasteading]

Yes. Changing the state of water from liquid to vapour absorbs a lot of energy, then you vent the damp air out of the building.

And repeat and repeat for many days.

Then suddenly you've got rid of the water and the fabric can warm.

Natural ventilation ( big draughts) can be as quick and no heating, but weather dependant. 

[SteamyTea]

Liquid water takes 4.18 kJ/kg.K.

When it gets to a vaporisation temperature, which is dependant on air pressure and ambient humidity, it take 2257 kJ/kg to change state.

Now myself and @Gone West looked into this a while back, and I think a common brick can hold around 8% of it's mass as liquid water.

Say a brick has a density of 2000 kg/m³, there could be an additional 160kg of liquid water to heat, and then convert to vapour.

Brick takes about 0.8 kJ/kg.K.

 

An ordinary brick has a mass of about 2.8kg, add on 8% water and that is another 0.2 kg.

To initially heat by 1 K will take.

0.8 [kJ/kg.K_brick] x 2.8 [kg] x T [T_final - T_original] + 4.18 [kJ/kg.K_water] x 0.2 [kg] x T [T_final - T_original].

 

2.24 [kJ/K_brick] + 0.836 [kJ/K_{water] = 3.01 kJ/g.} 

 

_{At vaporisation point.}

 

0.8 [kJ/kg.K_brick] x 2.8 [kg] x T [T_final - T_original] + 2257 [kJ/kg.K_water] x 0.2 [kg] x T [T_final - T_original].

 

_{2.24 [kJ/KBrick] + 451 [kJ/Kwater] = 453 kJ/g.} 

 

A huge difference.

Though it does not happen all at once.

[Gone West]

4 hours ago, Murph1603 said:

Hi Guy’s, just wondered what was everyone’s opinion on initial heating of a new build and heating the fabric of the build and the drying out I.e will the moisture absorb more heat until dried out as such 

 

56 minutes ago, SteamyTea said:

Now myself and @Gone West looked into this a while back, and I think a common brick can hold around 8% of it's mass as liquid water.

 

We moved into an old stone bungalow, with 600mm thick walls, which had been empty for a year. It is in Cornwall and we found, after we moved in, that it took months for the fabric of the building to dry out. We moved from a lightweight timber frame, timber clad Passivhaus in East Kent which, excluding the concrete slab, only took a week to dry, which was for the plaster skim and that was it.

[Murph1603]

I’ve nearly finished a self build timber frame bungalow, standard timber kit with 50mm cavity then 4” high density blocks with dry sash render, it’s taken 18 months and just wondered before carpets go down how long it’ll take roughly to start holding heat better, as it standards no carpets yet and heatings only on when we are there as heating controls haven’t been finished so it’s currently on a plug top so only taking it up to 12 degrees roughly before we knock it off