Heat for the kitchen, halls, staircase

Gene Davis_3

I am trying to figure out heating needs for a small new house I'm designing, and have gone through all the rooms on the main and half-story up.  Am using SlantFin's Hydronic Explorer 2 for the calcs.

Left to do is a group of spaces that all are part of the central common areas, all without walls, so that airflow and heat flow pretty much unimpeded throughout.

It is these areas I don't quite know how to treat:  kitchen, the adjoining hallway that is between kitchen and staircase, the staircase, and the upper hall and gallery at the top of the stairs.

I treated the small foyer as a room and calculated heat loss, and did the same for the large greatroom, in which are eating and sitting areas.  But these "rooms" open to the kitchen, and the kitchen opens to the hall, while that gallery upstairs is open to the vault above the greatroom.

See the plans here for floor one and floor 2.  In the next post in this thread, I'll show section cuts to give a better feel for the volume of space.

Gene Davis_3

Here are the section cuts

As can be seen, there is a window adjacent the winder staircase, midway up in the adjacent outside wall.  That wall is double thickness and can be heavily insulated, if required.  Directly above, in the vaulted ceiling over, is a skylight.

The kitchen really has no exterior walls, but since none of its volume was added to either the adjacent greatroom (22,670 Btu/h) or foyer (1,596 Btu/h), getting any heat in there whatsoever will rob from those adjacent spaces.

And, while the down and up halls are interior rooms, also, the up one has an attic above, so there is heat loss there as well.  And the staircase, with its exterior wall, window and skylight, and attic over, has a lot of heat loss.

How would you work the calcs to arrive at a heating need?  There is a spot in that winder staircase, in the "U" shaped space (it will actually be squared and not rounded as the plans show) there is plenty of room for a panel radiator, but I would like to know how best to size my need for heat.

A panel radiator there will radiate some heat across the small narrow "hallway" and into the kitchen space, and will throw a lot of its output straight up and into the volume of space above with the staircase on one side, and the upper gallery/hall on the other.

I think we would benefit from a ceiling fan hanging down in the center of the vaulted space over that tall greatroom, also.  Right?

Steamhead

What I'd do

is calculate the load within and above the stairway and add it to that of the first floor hall, then hang one panel rad under the window above the stairway with about 2/3 of that total load, and another one sized to the remainder in the first floor hall "U"-shaped area to keep cold drafts from coming down the stairs.



The kitchen load, which should be quite small, can be added to that of the great room. Since everything is so open it will not need its own radiator.



And you're right about the ceiling fan.

CMadatMe

How about Some

Radiant Panel Baseboard under the kitchen cabinets. I sent you some info on panel rads in your previous threads. The panel board should fit nicley right under those cabinets, you can keep with the 3/8 pex and trv's.

Mark Eatherton

Why worry about it...

Gene, You are splitting fine hairs.



Hallways and stairways are transitional areas. No one is going to be hanging out there, reading a magazine and drinking coffee. Besides, the loads are extremely low in any case. I have never worried about providing heat to those areas unless they will be highly glazed and regularly occupied. Now that we have radiant glass, treating them (highly glazed areas) is even easier yet.



As for the kitchen, when you have your stove running, coffee pot, and other heat generating appliances, you will probably have MORE than enough heat for that non load area. Infiltration is virtually the only loss you have to cover there, and it should be minimal.



Also, based on many years of experience, I have NEVER seen ANY building that I designed the heating system for running at 100% of capacity at design condition. The worst case scenario has been 50%. That means that the physical plant is twice as large as it needs to be.



In your case, when coming out of a deep set back condition, using remote control technology, the system during pick up might approach 100% of capacity, but once the internal mass is charged up, maintenance BTU's will be about half of what you'd expect, even at design condition.



My suggestion would be to spend more time and money in controlling uncontrolled ventilation issues (air bypasses between the crawl space and the attic) and tightening up the thermal envelope and the air barrier envelope (one in the same if properly done) and not worry about heating those minimal load transitional areas. You will get a better return on the investment, and a higher degree of comfort.



Consider doing an interim blower door test once you have the building dried in, and address those building leaks BEFORE they get covered up and expensive to gain access to.



Make the home tighter than a ducks butt, and throw a controlled means of ventilation (HRV or ERV) into the mix.



If you are really concerned with kitchen comfort, consider a radiant counter top and radiant wall at the knee hole. Just don't forget to place strategic insulation behind the heat source to make sure YOU have control over the directional flow of heat energy.



You know those cold, unfriendly granite countertops that you were thinking about? they CAN be tamed :-)



The Europeans have actually constructed passive homes with loads of less than 5 btu/sq ft /hour that don't require an auxiliary heating system. It is probably the typical "Euro Cave" conditions (If you are cold, put on a sweater), but nonetheless, it can be done.



ME

Gene Davis_3

I hear you, Mark

It's the engineer in me that makes me overthink these things.

I ignored the kitchen completely in the analysis, but since that hall with its staircase adjacent, the large section of exterior wall above, the skylight over, and the door with its access to the crawlspace below, seemed to be a volume of space for potential heat loss through its exterior surfaces, I decided to treat that two-story space as one more room.

Hydronic Explorer 2 told me to expect about 2,000 Btu/h heat loss there, under those design conditions of -20 F., and so I thought it might be good for comfort if a small panel radiator was placed in the U of the staircase.

Your points about the tight envelope are well taken, and that was planned from the start.  We have learned to frame for windows with a minimum 1/2" R.O. clearance all the way round, then use foam to seal.  Lots of foam.  We foam-insulate all critical areas such as rimjoists, attic edges under and against roof chutes, and more.  We caulk and seal until we cannot find any more leaks.  And yes, we blower-door test.  Baths are vented via Fantech HRVs.  Fireplaces and stoves are airtight units, with outside air intakes.

Ceilings under roofs in this house will get R-38 fiberglass between all trusses and joists, then a 2" layer of rigid foam up against the structure from the bottom, all taped and caulked and foamsealed, then strapped for the finish.

We use the airseal boxes for electrical boxes in exterior walls, and caulk all entry ports for the wiring, then seal the boxes to the wall finish.

We try to get everything so you can heat with a light bulb, but of course, you cannot.

Kevin_in_Denver_2

Heating a superinsulated house

Gene,



I recommend reading all the comments on a thread over at Greenbuilding Advisor, on this very topic.



Bottom line is that a superinsulated house is an isothermal house, no matter where the heat source is (and you leave the bedroom doors open).



http://www.greenbuildingadvisor.com/blogs/dept/musings/heating-tight-well-insulated-house

NRT_Rob

be careful

nothing Gene is saying would qualify the house as 'superinsulated' as far as I can tell. superinsulated homes don't have 20kBTU/hr great rooms.



My in-laws live in a superinsulated home. they retrofit radiant floor a couple years ago. they seem to think it's made quite a difference, actually, even though I advised them not to do it thinking along the lines of what mr. Wilson talks about.



It still makes a difference over cold space, it seems.

Mark Eatherton

I understand Gene...

Old habits are hard to break, but oversizing ANYTHING  (other than emitters) is not a good idea. It will result in system inefficiencies during the shoulder seasons, which is basically the majority of the time.



With ModCon appliances, over sizing has less of an impact, but I sit here on days that are marginal calls (45 to 50 deg F OSA) and hear my undersized heat source short cycling, and it really makes me wonder... and it IS a mod con.



Had I sized it per the load calc, it would have been TWICE as big as it is, and it would be short cycling TWICE as much as it is.



And my home is very comfortable.



Looks like you intend to do a great job of tightening up the envelope, which is a very good thing.



ME