Building retirement home off grid

[Mike Rugy]

Have started the build on our retirement home which is off grid.
The "battery room" along with the inverter and controllers will be in the crawl space.
Height of the crawl space varies from 4' to 4'9".
Room is all concrete along with the ceiling-main floor. All walls will be insulated on the back side of the crawl space walls as to have no combustible in this room.
My question is how to vent the room so that I won't have any issues with the Hydrogen gas.
One thought is to have the air supply 1.5 or 2 inch pvc pipe come into the battery room high on the wall from outside.
Once in the room horizontally 7 feet then have a 90 degree taking the supply pipe to within 5 inches of the floor.
The Vent pipe could be located 12 inches beside the intake pipe or should I vent up through the roof.
Another option is use the HRV to vent. Not sure but what would happen if an explosion takes place and pushes air into the heat exchanger which could or will get into the living area.
Any thoughts or comments would be much appreciated.
Thanks for reading.

[Sunking]

If you have a high spot in the room all you need is a vent to the outside that rises. Otherwise a hydrogen detector and forced air ventilation. Hydrogen levels must get to 4% before it can ignite.

[russ]

Just be sure to vent the highest place in the room to the out of doors. Do not leave a high pocket where hydrogen can accumulate.

[Mike Rugy]

The underside of my suspended slab would be flat and level.
Are you saying that I should have a bit of slope to where the vent pipe would be ?
Think that this what your saying. Like an upside down bathtub drain.

[organic farmer]

Is this in a region where radon issues are common in basements?

If so, a regular radon mitigation system would be in order, and that would also address H2 build-up.

[Mike90250]

..... Hydrogen levels must get to 4% before it can ignite.

HA ! you mean hydrogen levels only need to reach 4% before it's explosive.. It's the gas with the widest range of danger, like 4% - 75% Gasoline is a wimp, with a very small explosive window 1.4% - 7.6% too rich and it won't burn.

But you are not going to get away with power vents.. you need passive venting because it's in a dwelling. Either holes drilled through the concrete or some spacer/gaps. It won't be energy efficient, and will leak a lot of heat. If it was in an outbuilding, you can use power vents that can fail.

[Mike90250]

And your plan to move a thousand pounds of batteries & acid into the basement, and bend over them to maintain them ?

Plan to deal with the sulfuric acid fumes from them (yes, even AGM can vent and release fumes and hydrogen)

[organic farmer]

A 4% concentration means different things depending on the volume of a room. A 20' X 40' space with 4' of clearance, has 3,200 cubic foot of volume. For 4% of that to be H2 you need 128 cubic foot of H2.

How much off-gassing do batteries do?


btw, for most of 20 years, I saw fellow crewmen crawling directly on top of 1,000 pound batteries, to service them. [monitoring fluid levels, etc]

[Mike Rugy]

We had to blast rock for 7 days to get the house sited "into the rock".
Didn't want to have it on stilts for seismic reasons and also no monolith at the waterfront.

Radon isn't an issue here but will still seal the crawl space slab as if it did. Slab will be heated as well.
Venting this area will become a heat loss area no doubt. Will try to create a heat trap with the pipe in order to minimize or
at least slow down this effect.
How much "off gassing" should I expect on a per battery basis ?

Getting the batteries into crawl space will be work but have a small beam directly over the opening into the crawl space.
Winch here to raise and lower a small platform which has 1500 lbs capacity.
The battery room is W8' x D20' x H4.5. In the crawl spaces that we have build before we typically have a six wheeled dolly to get things around the space a little easier. Besides being 6'-1" in a crawl space its easier to roll around on the dolly.

Will have three separate crawl spaces in our home.
The crawl space for the batteries will also have the conduits/cables for the micro hydro stations.
Is it ok to have the inverter and controller and charger in the same room as the batteries or should they go into the next crawl space on the
adjoining wall. Another words back to back walls ?
Thanks for the input and suggestions.

[Sunking]

Sure hope you have no building codes or inspectors to deal with, because if you do none of what you planned will fly, nor will your home insurance underwriter will right you a policy.

[Mike Rugy]

Sure hope you have no building codes or inspectors to deal with, because if you do none of what you planned will fly, nor will your home insurance underwriter will right you a policy.

How so ? Please let me know what my concerns should be ?

Have a BP in place as well as a COC.
Appreciate all input.

[organic farmer]

We had to blast rock for 7 days to get the house sited "into the rock".

Not granite I hope, that is where radon problems are worse.

... Radon isn't an issue here but will still seal the crawl space slab as if it did

'seal' ?

Radon is usually dealt with by ventilation, not sealing.

... Slab will be heated as well.

I have heated flooring.

Heating a slab requires a great deal of underground foam.

... Is it ok to have the inverter and controller and charger in the same room as the batteries or should they go into the next crawl space on the adjoining wall. Another words back to back walls ?

They can go in the same room.

[Mike Rugy]

Luckily radon isn't present where we are building.
If it were then yes venting would be required.

Here all SOG that are heated require R12 under the slab along with 6mil poly taped and sealed at all edges. We will have R24.
Our building site is on an Island with no ferry access, no store, school, hospital no anything. So every thing is brought by boat or barge. Costly.

My challenge is to build the home so that I will be using as little resources/fossil fuel as possible once home is completed.

Good to hear that I can have the controller and inverter in the battery room.
Thank you.

[russ]

A 4% concentration means different things depending on the volume of a room. A 20' X 40' space with 4' of clearance, has 3,200 cubic foot of volume. For 4% of that to be H2 you need 128 cubic foot of H2.

Nope - the H2 will collect at the highest point in the room - it will not be evenly distributed.

[organic farmer]

...
Here all SOG that are heated require R12 under the slab along with 6mil poly taped and sealed at all edges. We will have R24.
Our building site is on an Island with no ferry access, no store, school, hospital no anything. So every thing is brought by boat or barge. Costly.

My challenge is to build the home so that I will be using as little resources/fossil fuel as possible once home is completed.

Our heat source is wood. Our woodstove heats water, which is stored in a thermal-bank, and circulated through our radiant flooring.