540 square feet vaulted to 12 feet. R40 insulation. 100 square feet of windows. Aprox 1300 square feet of wall. What will be the best costs effective solution to heat and cool. Winter low temp.-30 but usually averaging in the teens. Summer high 95 but usually in low 80's.

More information would be needed to determine heat loss or gain for space. Without knowing what energy sources are available and the cost of energy in your area it is difficult to advise you . With all that being said, a mini split heat pump with some auxillary heat strips would be more than likely my first choiice.

What type of info do you need? We can use propane ( 2.09 a gallon), all ready on the property. Electricity (Energy Charge per KWH: $0.04833)

Mini split heat pump is the ticket. You will need electric auxillary heaters for those extreme cold days.

To do a proper heat loss analysis you'd need to know glazing type/u-values not just area, as well as framing type, slab/basement R-values, the U-values of the doors, the assumed or measured ventilation rates (natural or mechanically induced) etc. Using the Taco freebie works for most of N.America:

http://www.taco-hvac.com/en/products/Taco%20Load%20Tool/products.html?current_category=370

"R40 insulation" means one thing if it's batts between 2x12s, quite another if it's R20 rigid foam on the exterior of R20-batt insulated 2x6, and something different still if it's a double-studwall or Larsen Truss wall assembly with dense-packed cellulose. At R40 center cavity the whole-wall R with the bridging of framing factored in runs about R25-ish, but 4" with exterior foam on a 2x6 it'll be close to R35, etc. No matter what the wall and roof construction, with R40 the U values of the 100' of window are likely to dominate the heat load numbers, and the orientation & type of said windows determines the solar-gain that has to be dumped during the cooling season.

At your propane & electricity pricing as well as your average seasonal conditions acwizard has it right- a lower-temp mini-split (Mitsubish H2i series or a low-temp Daikin) with some electric resistance backup for the cold-snaps is probably going to be the most cost-effective (and still pretty efficient) approach. With outdoor temps in the teens they'll achieve a COP of ~2.5, but that drops to under 2.0 at around +5F, and about 1.5 @-10F. The H2i series mini-splits still deliver ~70-75% of rated output @ -13F and are still better than break-even for COP, but don't count on being able to run them at all at -20F or colder, and even if you did, electric baseboards would be as-efficient.

It is a blank slate right now. The upstairs of a gambrel barn. Not insulated yet. Steel barn, wood floor that will get 4 inches of blue board between the plywood decking and finished floor. We will be using one(maybe 2) inches of blue board on all all walls and ceilings and then blown in celulose (that is the plan right now.) Only windows on the north wall, double pane clad (Kolbe I think but not sure).

This will be an art studio.
Down stairs will be unheated.

If the downstairs is being used for human habitat then heating will be required by code. Being that the upstairs is going to be an art studio, the first question which comes to mind is how valuable are the pieces of artwork that will be in the space. Art studios usually have close tolerances for temperature and humidity .You may be find with a minisplit for heating or cooling but dehumidification or humidifiers may also be needed. One must first determine the specifications for the controlled enviroment before hvac equipment could be chosen.

It's a barn, the downstairs will not be heated. No animals inside. The artwork is oil paintings and do not require special temps other than above freezing and not too hot. This is an existing building about 4 years old. We can go any way we want within reason.

Posted By jmagill on 12 Sep 2011 04:54 PM
It is a blank slate right now. The upstairs of a gambrel barn. Not insulated yet. Steel barn, wood floor that will get 4 inches of blue board between the plywood decking and finished floor. We will be using one(maybe 2) inches of blue board on all all walls and ceilings and then blown in celulose (that is the plan right now.) Only windows on the north wall, double pane clad (Kolbe I think but not sure).

This will be an art studio.
Down stairs will be unheated.

Independently of whether the blue board is on the interior of the cellulose that may not be sufficient R (or vapor retardency) to be fully protective from moisture drives.  This is climate, stackup, and total-R dependent, and may need some adjustment for your actual location.

Air leakage at windows can be large loss factor in high-R buildings.  Using windows that don't open makes it tighter, as does using casements or awning windows rather than single/double-hungs or sliders.  Casements & awnings also provide the greatest amount of egress area per unit area of glass too.

Taking a rough cut at the heat load: 

At -30F outdoors, 70F indoors, 100 square feet of U-0.30 low-E window represents a heat loss of 3000BTU/hr, not counting air infiltration. 

Then, assuming you get a true R40 out of it, 800 square feet of ceiling/roof is  worth another 2000BTU/hr. 

With R20 under the floor, and assuming the lower part of the barn doesn't drop below -10F on -30F night (a big assumption), the floor with it's 4" of XPS  is another 3200BTU/hr.

Assuming an average wall height of 10' and a 20x40' footprint for ~1200' of wall, and assuming you can get about R30 out of it, that's another ~4000BTU/hr.

That addsl up to ~12-13K, before infiltration & ventilation losses- call it 15KBTU/hr, which is supportable by 3.5kw of electric baseboard. 

If it's ~15K @ -30F,  0F you'd be looking at 10-11K, which a 1.5 ton mini-split could keep up with reasonably efficiently, and still provide 100% of the heat all the way down to -5F or -10F or wherever the particular unit's low-temp operating limit is.

But you have to be sure the R/U values are designed & built into it correctly- thermal bridging of joists & studs robs the assembly of a significant amount of thermal performance. For a good primer on high-R walls see:

http://www.buildingscience.com/docu...gh-r-walls

Look at table-3, p 13. Your wall stackup seems most-similar to case 2a & b, with perhaps different foam thicknesses.  Even though case 2b has a center-cavity R of ~ R40, as would 4" of foam with a 2x6 cellulose cavity fill wall,  it's actual whole-wall (all thermal bridging of the framing factored in), is only R34.  If you go thinner foam, thicker cellulose retaining a R40 center-cavity value, the thermal bridging of the studs/joists will be higher than in the examples cited, and the whole-wall R even lower.

There are a lot of options for heating or cooling a large area like 800 sq feet.
You can get in touch of heating and cooling experts to get a more accurate measurement and best suggestions for your inquiry.

Posted By davidsbreslin on 20 Sep 2011 01:42 AM
There are a lot of options for heating or cooling a large area like 800 sq feet.
You can get in touch of heating and cooling experts to get a more accurate measurement and best suggestions for your inquiry.

I am getting in touch with the experts. Right here on this site. I have sparred enough with them to know that they know what they are talking about and I respect their opinions( even if I disagree sometimes)

Greetings,

A 3 layer RB insulation sys will out perform any that are being suggested here. The sys I suggest to my clients has only about 2 btu/hr/sq ft transfer. You should also use a 2 layer RB in the floor as there will be considerable heat transfer in winter. You will have no mold or moisture problems and a sys that will last as long as the building. You will also have to pay special consideration to the ceiling installation, which you'll notice no one has addressed.

Keep in mind that "R" 30 -40 is a fictitious number. These values are NOT based on installed condition tests.

NBS tests show that as soon as moisture has condensed in FG or Cel you will have a 50 - 72% increase in heat flow, and that is in an unoccupied building.

Posted By rbisys1 on 27 Sep 2011 07:36 PM
Greetings,

A 3 layer RB insulation sys will out perform any that are being suggested here. The sys I suggest to my clients has only about 2 btu/hr/sq ft transfer. You should also use a 2 layer RB in the floor as there will be considerable heat transfer in winter. You will have no mold or moisture problems and a sys that will last as long as the building. You will also have to pay special consideration to the ceiling installation, which you'll notice no one has addressed.

Keep in mind that "R" 30 -40 is a fictitious number. These values are NOT based on installed condition tests.

NBS tests show that as soon as moisture has condensed in FG or Cel you will have a 50 - 72% increase in heat flow, and that is in an unoccupied building.

According to the ORNL Large Scale Climate Simulator testing, the modeled whole-wall values of those stackups are pretty close to reality.


And the efficacy of any 3-layer RB in a studwall doesn't meet code-min for heat loss/gain anywhere. (Also confirmed by ORNL &  EN guarded hot-box testing.)

It's also "strange but true" that moisture doesn't actually condense on fiberglass or cellulose fiber insulations themselve under typical residential moisture drives, but instead rapidly migrates onto the coldest structural elements (exterior sheathing in winter, interior wall-board in summer) when those materials are below the dew point of the air in the cavity, lowering the RH inside the insulation layers.  Only under truly extreme moisture drives does the moisture content appreciably change the insulating value of the fiber material.  (Condensation or frost on RB also dramatically increases it's emissivity, but of course according to rbisis1 that simply never happens. )

Posted By Dana1 on 28 Sep 2011 10:56 AM

Posted By rbisys1 on 27 Sep 2011 07:36 PM
Greetings,

A 3 layer RB insulation sys will out perform any that are being suggested here. The sys I suggest to my clients has only about 2 btu/hr/sq ft transfer. You should also use a 2 layer RB in the floor as there will be considerable heat transfer in winter. You will have no mold or moisture problems and a sys that will last as long as the building. You will also have to pay special consideration to the ceiling installation, which you'll notice no one has addressed.

Keep in mind that "R" 30 -40 is a fictitious number. These values are NOT based on installed condition tests.

NBS tests show that as soon as moisture has condensed in FG or Cel you will have a 50 - 72% increase in heat flow, and that is in an unoccupied building.

According to the ORNL Large Scale Climate Simulator testing, the modeled whole-wall values of those stackups are pretty close to reality.


And the efficacy of any 3-layer RB in a studwall doesn't meet code-min for heat loss/gain anywhere. (Also confirmed by ORNL &  EN guarded hot-box testing.)

It's also "strange but true" that moisture doesn't actually condense on fiberglass or cellulose fiber insulations themselve under typical residential moisture drives, but instead rapidly migrates onto the coldest structural elements (exterior sheathing in winter, interior wall-board in summer) when those materials are below the dew point of the air in the cavity, lowering the RH inside the insulation layers.  Only under truly extreme moisture drives does the moisture content appreciably change the insulating value of the fiber material.  (Condensation or frost on RB also dramatically increases it's emissivity, but of course according to rbisis1 that simply never happens. )

Here is my response. http://www.greenbuildingadvisor.com/blogs/dept/musings/radiant-barriers-solution-search-problem

Sorry that was not for Dana but rbisys1

Not a big fan of forced air heat pumps and I would look at using a smaller mini split A/C and radiant panels a lot more comfortable and quite probably not as energy efficient but not far off. Check these out http://www.sshcinc.com/applications.htm As far as sizing i think Dana is pretty close..