Question about ventilation

I understand that to meet residential building codes, you have to have fresh air circulation if the windows are removed. Does that fresh air have to come from outside the house? I am trying to figure out the air/heat part of making a studio in the home, and my mind can't seem to get around it. The studio is not going to be a big money maker for me, so I am hesitant to spend thousands of dollars on a separate heating/AC unit. Could I build in a system where air is taken in from one part of the house, pumped into the studio, and then blown back out to another part of the house? Would this meet code? It seems like this would allow me to get away with less heating/cooling, as the air in the house would already be the correct temperature. Am I completely off base here? I am trying to come up with a plan before we move in to our new house, so that I can get started as soon as possible with the studio. There are just a few things that are not sitting right with me, however, and HVAC is one of them.

Mark Blasco wrote:

I understand that to meet residential building codes, you have to have fresh air circulation if the windows are removed. Does that fresh air have to come from outside the house?

Yes, it is. I consdered supplying my room with "semi-fresh air from the house," but that idea was knocked down by my building department (and by code). Fresh air mechanical ventilation has to come from the outside, and the exhaust air must go directly outside as well (i.e., you can't take a shortcut and push the exhaust air into the attic or a garage). --Keith :mrgreen:

Well, I am really stumped. How do you run fresh air from the outside into your house without having to constantly run a heater or air conditioner? It seems like any benifit of insulation to keep the temperature stable would be ruined by the fact that you are bringing in air from the outside. Is there a way to meet the fresh air code requirement without having to install a second Heat/AC unit in the house? Does someone have a link to somewhere that explains what I need to get to meet this requirement? Is there a way to do windows to the outside without significantly reducing sound isolation? I am confused.

The ventilation system does not have to be on all the time, just as windows need not be open all the time. It's just that the system needs to be able to be activated on demand by the room's occupant(s). A Heat Recovery Ventilator, such as the Fantech HRV-1404, can be used, which will (supposedly) recycle heat in cold weather and transfer heat in hot weather. See the "Is this overkill? Studio AC wiring layout" layout thread, especially the very end, where koberlin1 posts about his success using the Fantech HRV-1404. See the point in my thread where I discover the Fantech HRV system and how I incorporated into my plan, in conjunction with a mini split air conditioner for cooling comfort. To answer your question specifically about whether or not there are ways to incorporate windows that won't affect isolation much -- yes, there are, but it's expensive, especially if they're operable. If they're not operable, then you're still at square one. Typically, though, operable windows are not found in studio designs due to sound isolation concerns. Here's an example of fresh air requirements for residential construction (City of Boise, Idaho, using IRC 2003). Don't assume that these requirements are exactly the same as those in your local jurisdiction -- you need to check with them for the details. However, that handout should help clarify some of the concepts. Hope that helps... --Keith :mrgreen:

Sharward, this has been very helpful, and I think I am starting to "get it". OK, the fantech unit seems to cover the ventilation issue, without having to purchase a whole separate heating/cooling system. How do you go about setting up one of those units for use in 2 rooms? Should the exhaust port go into one room, the fresh air port into the other, and then connect the 2 rooms? Do you split the input and output at the unit, and run them to both rooms? I am a little unclear as to how you would use one of these units for a studio(in my case for a control room and a large iso booth, which is around 1/2 the size of the control room) Another question - are there building code requirements for heating/cooling? The house we are moving into has air conditioning (which is rare here in seattle), and I can always just leave the doors open to the rest of the house most of the time to help with temperature. I am wondering if this fantech unit will be enough, even if I don't have a separate heating system. Maybe I could have a system to pump air in and out of another room in the house to help keep the temperatures under control, and the fantech unit for the fresh air.

The Fantech VHR installation instructions do show that you can split the lines. After all, these units are designed to ventilate an entire house, not just one room. (Although, I think they would work extremely well for a single or double room studio, where the ventilation replaces operable windows.) However, for maximum isolation, you should not structure the lines like they show in their diagrams -- rather, do a "home run" configuration (i.e., from unit, to a "Y" split, and then each end of the "Y" going to each room). For specific heating and cooling code requirements, talk to your local building department. Really. There's no substitute for getting face-to-face with them with your cocktail napkin sketches, with a winning attitude about striving to do everything to code. They love that crap. ;-) Honestly, though -- I would imagine that you'd need air conditioning. Have you ever been in an air-tight studio environment that was too chilly? ;-) (That's easy for me to say right now -- our outside temperature right now is 99°F (37°C)! :lol:) --Keith :mrgreen:

Keith, your point about being it never being too cold in a studio is sound, but unfortunately for me, the budget I have for this project may make it impossible to have an AC unit. It is not just because of the cost of the unit, but I don't have any extra space on my electrical panel to add circuits, and I have a feeling I will have to upgrade my electrical panel or add a second panel (if that can even be done) in order to make the VHR part even be a possibility. At this point I may end up running the wiring for an AC unit, as well as the ducting, with plans to add the unit later on as the budget permits, and see how well it works with just the VHR. I can also always open up to the house, which does have AC, and just make sure to close all the doors when tracking. Any suggestions on an AC unit for a smaller area (both rooms probably won't exceed 400sf total)?

The mini split, such as Mitsubishi's Mr. Slim line, is probably the best option for cooling such a small space, although they're not cheap at all. :roll: What I might suggest is preplumbing for one (which will cost a few hundred dollars) and then installing it later if necessary. Another option may be the "chiller room" concept, using an inexpensive window air conditioner, such as that detailed in dietcookie's "from shed to studio?" thread. You might also check out "Marc's Patio & Garage Studio" thread, which includes an electrical service panel relocation (and expansion I think?) -- something he grappled with quite a bit before biting that bullet. --Keith :mrgreen:

The electrical panel is something that I didn't give too much thought to in terms of location, but now that I think about it, it may be a big problem. I will start another thread about this to try to get some opinions.