Passivhaus - an idea to cool a pantry

[RedRhino]

What’s the difference between a large cupboard and a pantry? A pantry is cool, or at least it should be. 
Reducing refrigeration saves energy and many foodstuffs (e.g. butter, bread, ale) should be cool but not cold. 

However, Passivhaus requires a continuous airtight, thermal envelope. Nowhere is cool. 
 

Here is my idea: locate the rising main in the pantry and T off the supply to a radiator or similar. When extra cooling is required open up the reservoir to divert water at ground temp through the radiator. Simple, low tech and nothing too novel for the trades to scratch their heads over. 
 

Smart or is there something I haven’t considered?

[Conor]

Where does the water go?

How do you manage condensation? Is it ventilated?

Is the room fully insulated?

 

 

(We wanted a cooled pantry room and even with an underground basement, looked into AC, ground cooled air etc, proved way too much hassle and expensive and we just have a second fridge)

Edited March 3 by Conor

[RedRhino]

Where does the water go? That is a good question. 
These thoughts are for our next build. Our current ICF house has a pantry on the north wall but it isn’t cold enough. 
 

I think the answer would be to have an MVHR extract duct in the pantry. We would have to have some air flow past the pantry door too. 

[PNAmble]

Having a cold area in a passive house - how would the work without creating condensation, you’d need to insulate around the ‘pantry’ and have an airtight door?  Or you could have a cold store in your garage or an extra fridge.  

[Conor]

4 minutes ago, RedRhino said:

Where does the water go? That is a good question. 
These thoughts are for our next build. Our current ICF house has a pantry on the north wall but it isn’t cold enough. 
 

I think the answer would be to have an MVHR extract duct in the pantry. We would have to have some air flow past the pantry door too. 

I mean the cooling water. You're going to have to use 1000s of litres a day to get any effective cooling. Does it recirculate to a ground heat exchange? Does it go down the drain? If it's just your daily home use, it may not be enough to make much of a difference. 

[RedRhino]

I envisage just using the domestic water feed as it enters the house with the option of it going through a heat exchanger (i.e a radiator).  No extra water consumption. 

Every time someone flushes the loo or washes their hands more cold water is drawn out of the ground. 
How much colder would it make the pantry? Water has a very high thermal mass but I guess there is only one way to find out. 
 

Our current pantry is slightly cool in winter, not at all cool in summer. It can’t be worse than that. 

[JohnMo]

7 minutes ago, RedRhino said:

option of it going through a heat exchanger (i.e a radiator)

Bad idea - You would have to very careful doing that. Would need to be copper or stainless and very clean, otherwise it would not be healthy to drink the water later.  And certainly don't want to get carbon steel corrosion products in you unvented cylinder as you start to get pin hole corrosion in a couple of years.

 

We had an 1830 build last, that had a cold room, thick stone floor, walls and 50mm thick stone shelves, never changed temperature year on year.  

 

A passivhaus doesn't necessarily mean exactly the same temperature everywhere. Really depends how you build the space.

[RedRhino]

Thanks for the comments - I agree with @JohnMo that you have to be careful diverting drinking water through anything unclean or that could corrode. 

 

FYI I measured the temp of the rising main as it enters our current house. It was 15c. I flushed the loo and it dropped to 10c. 

The rising main is in our 'tech room' with MVHR / water tanks / gas boiler / washing machine and clothes drying racks. 

The rising main is beaded with condensation but the room is vented via the MVHR so we have no other damp issues. 

[JohnMo]

17 minutes ago, RedRhino said:

gas boiler

Sorry slightly off topic, really consider an ASHP.  My build started with a gas boiler and although not passive, getting the gas boiler to work efficiently in a low energy demand house isn't that easy. Our max heating demand is 3.5kW, but most the heating season you need less than half of that.  Had two heating seasons with gas boiler and then self installed an ASHP. We have plenty of solar, battery and on E7, but even in Dec and Jan when solar is rubbish the ASHP is cheaper to run than gas. And it's easier to get running well on low heat demands.