Air Conditioning without external unit

[hywyn]

Hi,
I am taking over a chapel that has been refurbished in the recent past and has ducting for an expelair system that is fine and works. However it has no air getting in. A problem because the conservation agency that works for the government has decreed that the outside of this old building should not be altered. I believe an air-conditioning fan would not be appreciated so, is there a system that avoids needing ugly exterior fans?
Cheers,
Hywyn

[Soundman2020]

Hi Hywyn, and welcome!

When you say "fan", are you talking about the ventilation fan, or the air conditioner compressor? Two different things...

If you can't have an external ventilation fan then you could just use an in-line fan in your duct system.

However, if you cannot alter the building exterior at all, then you have a major problem: regardless of where you place the ventilation fan(s) for your HVAC system, you still need the ducts to enter and exit to the outside world at some point, and you still need a place for your compressor or heat pump: those HAVE to go outside, for obvious reasons: their very purpose is to transfer heat between the inside of the building and the outside world. If you can't put anything in the outside world, then you are pretty much hosed.

Perhaps something really expensive like a geothermal system might be possible. At least with that it can probably all be done within the building footprint, with no visible changes on the exterior. But even then that only takes care of the thermal aspect of HVAC: You still need to get fresh air in, and exhaust stale air out, and that implies vents some place. Maybe underground ducts leading to an outbuilding of some type?

But all of the above is rather pricey...


- Stuart -

[hywyn]

Hi Hywyn, and welcome!

When you say "fan", are you talking about the ventilation fan, or the air conditioner compressor? Two different things...

If you can't have an external ventilation fan then you could just use an in-line fan in your duct system.

However, if you cannot alter the building exterior at all, then you have a major problem: regardless of where you place the ventilation fan(s) for your HVAC system, you still need the ducts to enter and exit to the outside world at some point, and you still need a place for your compressor or heat pump: those HAVE to go outside, for obvious reasons: their very purpose is to transfer heat between the inside of the building and the outside world. If you can't put anything in the outside world, then you are pretty much hosed.

Perhaps something really expensive like a geothermal system might be possible. At least with that it can probably all be done within the building footprint, with no visible changes on the exterior. But even then that only takes care of the thermal aspect of HVAC: You still need to get fresh air in, and exhaust stale air out, and that implies vents some place. Maybe underground ducts leading to an outbuilding of some type?

But all of the above is rather pricey...


- Stuart -

Hi Stuart,

thanks for the reply and advice, - I barely took the time to introduce myself or explain this project in clear detail (I shall do this on another thread) as this sudden realisation of the need for air caused some panic!

Being a novice of issues regarding HVAC, the 'fan' I referred to is the big one I always see on the outside of buildings.

There is an elaborate system of ducts in the ceiling and vents have been created already to expel air, - these can I presume be converted to dual use for a HVAC system.

The building is heated using underfloor heating, therefore no need to transfer heat in, but does the need to transfer heat out require a compressor / heat pump to be placed outside? I would presume that the noise generated would be adequate reason to do so.

Regarding the need for external modifications needing to be sympathetic to the building, there is perhaps an alternative in using the big space next door to the live room which is a glass atrium (24 feet high and perhaps, 20 feet wide, 20 feet deep). I presume this would have enough volume of air to be recycled for a HVAC system, feeding a studio. There would still be a need to install something which isn't an eyesore, as it will be viewable from the outside and would therefore need to pass the buildings criteria.

It's a head scratcher!

Best regards,
Hywyn

[Soundman2020]

Being a novice of issues regarding HVAC, the 'fan' I referred to is the big one I always see on the outside of buildings.

That could be anything! Buildings have fans for both the air conditioning system itself, and also fans to move fresh air through the building. And also fans to cool equipment. And also fans to remove smoke/odors from certain types of rooms (kitchens, bathrooms, etc.). And also fans for other purposes... You might have seen any or all of those on different buildings.

There is an elaborate system of ducts in the ceiling and vents have been created already to expel air, - these can I presume be converted to dual use for a HVAC system.

Probably, but you should check with someone who knows for sure: You might need to hire an HVAC technician to take a look at what is there and prepare a report for you, explaining in writing what you have, and what its capabilities are.

but does the need to transfer heat out require a compressor / heat pump to be placed outside?

Yes. But you need to calculate how much heat needs to be removed, both latent heat and also sensible heat, and you need to do that using the numbers for how much heat your equipment is generating, and how much heat and humidity the people in the rooms are generating, and also how much heat your lights are generating, as well as any other heat sources. There's a LOT of calculation that goes into designing your HVAC system.

You can't just guess here: you need to get the real numbers, and design accordingly.

- Stuart -

[hywyn]

Thanks for this Stuart. Your advice is spot on, - I need to get the experts in for this. I'm in touch with a company called DBX acoustics in UK who seem very attentive to the details and will I'm sure test and advise accordingly. i am also seeing a 'conservation officer' tomorrow, who will advise where it might be possible to place the plant machinery. It's tricky as this building is not allowed to be visibly altered.

Steve