We’re building our house soon. It’s exciting but we would like to improve the design to above code and reduce the heat loss. We’re located about 1 hour north of Toronto, Canada (L9W 1E5)

The main level is 3,700 sqft, with a walk-out basement of 3,700 sqft (basement includes a 1,200 sqft garage). The shape of the house is rectangular. 8ft ceiling in basement, 9ft ceiling in main floor, though some parts are vaulted to 13ft.

Construction methods:
- Foundation: poured concrete
- Main level: 2x6 framing with stucco exterior

Heat Loss (calculated by HVAC contractor):
- 76 Temp difference (-6F to 70F)
- 75,000 Btu/h
- 6,200 Sqft
- 33% - Infiltration
- 19% - Windows (730 sqft)
- 13% - Walls (4,300 sqft net)
- 13% - Ventilation
- 12% - Floors (3,700 sqft)
- 9% - Ceilings (3,700 sqft)
- 2% - Doors (260 sqft)

R-Value Assumptions (design specs included):
- Windows (1.7 u-factor. Windows are double pane with argon gas)
- Walls above grade (R22)
(Design specs: 2x6 & EIFS wall c/w 1" rigid insulation, 7/16" OSB sheathing, 2x6 wood stud @ 16" o.c. c/w R-19 Batt Insulation, 6mil Poly vapour barrier, 1/2" dry wall)
- Walls below grade (R20)
(Design specs: Dimpled membrane, asphaltic emulsion dampproofing, 8" thick conc wall, 1/2" airspace, 2x6 wood studs @16" o.c. c/w R-20 Batt insulation, 6 mil Poly vapour barrier, 1/2" drywall)
- Slab (R10)
(Design specs: R-10 Perimeter insulation)
- Exposed floor (garage) (R31)
(R-31 Poly-urethane insulation)
- Ceiling with attic space (~60% of space) (R50)
(Design specs: R-50 Insulation, 6mil poly vapour barrier)
- Ceiling without attic space (~30% of space, limited by the ends of the vaulted ceilings 4/12 interior, 6/12 roof) (R31)
- HRV Minimum efficiency (55%)

We have plans to insulate further under slab and the maybe inside of concrete walls. We looked into ICF but it was twice the price of poured concrete foundation. $73k vs $30k.

For the stucco exterior, we are looking at 1.5"-2" rigid insulation as opposed to 1" listed in the design

As for triple pane glass, a windows guy recommended against it because it increases the weight of the sealed unit it rips it apart. It reduces the life span of the windows by 5 years and the failure rate is larger, extra strain on window hardware,

What exactly are the wall and ceiling buildups to get the R-value assumptions? Seems like a lot of infiltration. When it comes to windows, the less you need, the better off you will be.

Sounds like ICF is very expensive in your area…presumably from labor markup. Have you considered DIY ICF?  Perhaps you could save as much as 80%. Perhaps get an estimate for the ICF materials.

Not a big fan of triple pane windows in general, but what exactly is this issue about?

My recommendations would be to increases your slab wall r values to 20, and make certain you isolate the slab sides, wall insulation by 50%, roof insulation to at least R60 and triple glazed windows. Triple glazed windows are fine as long as they are built for the glazing; do not buy them from "the windows guy" since he clearly either deals with poor windows, is selling "against" them, or knows nothing. I sold paint in college; some people said the other brand was junk because ---(fill in the blanks); a smart manager told me that that type of sellling only degrades your own product.

yes this type of building costs more. Of course it is. It is worth it for both long term value, comfort, and dollar savings over the years.

Is the basement Heated? hard to tell from your specs?

Infiltration Your infiltration plus ventilation number is 47% of your heat loss. That is crazy
IF we are assuming that the heated portion of the house is 3750 sf over a full size basement with parking under. Assuming that the average wall height is 10’ you get a volume of 37,500 cubic ft of heated space IF you set a value of 2 ACH50 (2 air changes per hour measured with a blower door at 50 pascals difference) this would give you a natural air change due to stack effect of ~ 0.1 air changes per hour which is 3750 cubic ft/ hour multiply this by 0.018 btus/ft3(heat content of air) *76°F temp difference= 5100 btu’s/ hour from infiltration. This represents a moderately well sealed value. If the basement is conditioned, add 30,000 ft3 to the volume, but it is easier to seal basements so shoot for 1.5 ach50. This would give you about 7000 BTU’s/hour. IF you are using a HRV, you can assume at least a 70% thermal efficiency and if you have 5 people in the house, you can set the HRV to 5*7.5 +0.01*7500 are around 115 cfm 115*60*0.018*76 *0.3= ~ 3000 btu’s/hour
I think you should be shooting for combined infiltration + ventilation losses to be ~ 10- 12 000 btu’s or less.
As far as windows goes, I would be specifying a window ~ U 0.16- 0.19 This will be a triple pane argon or krypton filled windows. The second part of this is that you want High solar gain windows on the south side, possibly on the east and west also- although this is more problematic unless you have a shading strategy. Tripple pane windows in cold climates offer some thermal benefits, but add huge comfort advantages due to the higher mean radiant temp of the rooms.
I would look at Kohltech tilt and turn Energlass Plus for south and mayby all sides, if not do the other sides with energlass plus LSG
Below grade, consider exterior FG- or Rockwool insulation to supplement the interior insulation. Google Warm N DRY for one example.

Cheers, Eric

Let's start at the beginning of all well designed residential buildings; and ACCA Manual 'J' heat load analysis. Each will be specific to the location and construction methods. The balance between the cost of equipment, operation cost without compromising comfort can be modeled before you start building. All the pertinent questions are asked, answered and calibrated using software accepted by every trade in the industry and reliable in the hands of an experienced operator. The rest is just a soap opera.

It does appear your numbers are off, but without a set of plans no one here, or anywhere, knows what you should or could do. These are questions for your builder and/or the "HVAC guy". If he can't answer them; you need a new guy.

Triple pane windows have one of the lowest return on investments in building construction, right up there with extra insulation under the slab. Extra-good triple glaze is worse.

http://www.greenbuildingadvisor.com/blogs/dept/musings/study-shows-expensive-windows-yield-meager-energy-returns

One of the most important factors in choosing windows is their orientation and your climate.

http://energy.gov/sites/prod/files/guide_to_energy_efficient_windows.pdf

DIY radiant floor heating design; always the first mistake.

Thanks for all the replies, I took a more detailed look at the house plan by my designer and added the insulation details in the plan.

@ BadgerBoiler - You mention the lowest return on investments, what would you say are the higher return on investment? Extra insulation under the slab was on the top of my list of modification.

@ Eric - Yes, we are planning to heat the basement. I'm not sure what assumptions went into the infiltration and ventilation assumption to get 35,000 btu of heat loss, though I assume it was all based on standard building code assumptions.
I'm glad to see that 10,000-12,000 btu is achievable for combined infiltration + ventilation. What would I have to do, or make sure is in the existing design to get this? Yes we plan on using a HRV.

@Bob - Yes we are looking to improve wall insulation, slab, and ceiling. What products do you recommend?

@Sailawayrb - I've added additional details from the house plan to the first post. I'm not sure at all why infiltration is that high, what can I do or make sure is there to reduce it?
I'm not really comfortable with doing DIY ICF because I want to make sure the foundation is done right. I do plan to make up for it by insulating on the inside.

Thanks for the additional details Mickey. I am sure Dana and others will weigh in with great suggestions for improving your building envelope R-value and infiltration performance…and there is good Return on Investment (ROI) there.

Having adequate slab insulation is very important. For HR system heated slab-on-grade floors, your minimum under-slab insulation R-value should be 0.125 x (Ti - To), where Ti is your indoor design temp and To is your outdoor design temp (in units of deg F).

Having this minimum under-slab insulation R-value tends to keep the downward heat loss to about 10% or less of the total heat supplied to the floor. This is typically considered a reasonable tradeoff between insulation economics and heating system efficiency. More insulation will improve your efficiency, but will also hurt your pocket book more...so there is a ROI to be considered here.

Mickey,
I am going to make a suggestion. What you really need is someone in your area that is a competent building scientist. You are going to need to sit down with them and your plans. It is not going to be free, but it will be worth it. I can make lots of suggestions, but I don’t know costs in your area, house layout, exact location, and local building codes, so it is somewhat difficult. In some cases, this is the heating contractor, but more often is an energy auditor in some form. You may want them to work with the builder to insure you hit air sealing targets and to act a QA.
You need someone to do a very careful heat load analysis based on the plans, and then make suggestions and explore your best options.
A house is a huge investment so you need to get it right.
Once you start building, you need to test it to make sure it is properly airtight, and you need to commission it to make sure it is working as designed. The best plan in the world fails if you don’t build it the way you planned. Look at the thread started by sky heating when a “high performance house” was built with poor airsealing and lack of detailing.
http://www.bluegreengroup.ca is somewhat in your area, Maybe too far away, but if they are I bet they could recommend someone else locally. I don’t know Greg Labbe, but I have read a batch of stuff he has written over the years and he seems very knowledgeable.
If you lived in Connecticut, I would happily suggest myself

Some of the questions I would want to answer before building:
Solar
I would look at the orientation of the house on the lot and what the shading factors are. What is the potential for passive solar? How would it line up for solar thermal or solar PV? How do roof overhangs help or hinder passive solar?
Do the windows support my solar strategy?
Do I need to worry about overheating in the shoulder seasons? How about exposure to west low angle summer sun?
Basement
How does the garage interact with the thermal barrier? How do I keep exhaust fumes and other volatiles stored in the garage out of the air in the main house? Ie Air Barrier details.
How do I deal with Radon?
What are the water management details for the basement foundation? What is the seasonal high water table?
If the garage is not heated, how does the room above deal with heat loss on 5 sides?
How do the basement wall assembly’s dry? Inward or outward? Is there a mold potential with the poly VB?
How is the walkout part of the basement slab thermally isolated from the heated space?
What is the underslab insulation detail? Is it thermally isolated form the foundation?
Framing
Is there a capillary break between the foundation and the framing?
Main framing in the house? Can you use 2x6 24”OC ie OVE construction? Insulated Headers? 2 stud corners?
What if you switch from commodity OSB to Zip Sheathing + tape for the air seal?
Can you increase the continuous insulation from 1” to 3”? How would this affect window and door installation and water management?
What is the best insulation strategy? BIB, Cellulose, rockwool, standard FG, foam?


What windows work best and where? Daylighting for interior rooms tubular skylights, etc.
How does the cathedral roof area work? Vented or unvented attic? Truss or conventional build? Can you use an energy heal to increase insulation potential? How do you transition from cathedral ceiling to regular attic?
How do you detail the air barrier when you transition from wall to ceiling?
When you answer all of these then you can start thinking about HVAC
Cheers,
Eric

the energy design consultant does not have to be in your area; they need to know where you are and what your goals are. These guys - Mike and Paul have a lot of experience in high performance building and could help you plan your house:
DEAPgroup.com

OMG. A huge house with minimal specs and probably sub-minimum execution, based on what they are offering you. This is the antithesis of green building.

I presume this builder builds everything this way, uses the same methods to calculate his heat losses, sizes the heating plant appropriately and has no past problems with undersizing?

Your infiltration numbers are suspicious. They shouldn't be that high unless your builder is telling you honestly that's what he gets with this kind of construction, in which case they are too high. :-)

It doesn't cost much to get an HRV more efficient than 55%, either.

I wouldn't worry about having triple pane windows until you get the rest of your envelope under control.

Have you considered the upgrade to 2" EIFS and blown-in insulation? Get rid of the fiberglass batts.

And, just to repeat what others mentioned, home orientation and the window sizing, specifications and shading are important.

@ICFHybrid - Actually, this house was never designed as a green build, it's a just a typical new construction. The heat loss was calculated by the HVAC contractor not the builder. I do want to improve it though, and will be looking into all the suggestions here. Yes, we are upgrading to 1.5" (maybe 2") EIFS and a better HRV, and will look into blown-in insulation. Both you and Eric raise a good point about making sure the execution is done right, so many houses in sub divisions around here have leaky rooms despite being built to code. This was one of the reasons we decided to build custom.

@Eric - Thanks, I will looking into the cost of sitting down with a Energy design consultant/ Energy auditor, it might be well worth it. The HVAC contractors I spoke with don't seem focused on heat loss reduction, they seemed to treat the heat loss as the constant, and were focused on helping me size the right heat option. A lot of those questions you asked are very new to me, so it seems like I have some reading up and thinking to do.

@Sailawayrb - Thanks, based on your formula it seems R-10 under slab insulation is enough from an efficiency/ ROI standpoint? (76 F temp difference = R9.5). If so , then this is already specified in the design.

Mickey, the good part is you are asking these questions before you break ground. Cheers, Eric

Mickey
How about an update on your house and what steps you have taken to improve overall efficiency?
I am going to start a new thread looking for input but my situation is the opposite of yours in that my issue is cooling not heating 7 months a year.
Look forward to an update...

First, a tight house is an efficient house. No more holes in the envelope than are mandatory for ventilation, fuel and electrical service.

R-50 attic.

Exterior rigid siding R-5 minimum, R-20 assembled.

R-10 exterior sub-grade walls with Roxul or equivalent.

Foam the rim-joist. There is no more effective way.

Double-pane, Low-E, argon filled, windows, U-Value .30, VT 60% and an SHGC dependent on your ultimate passive solar considerations.

But for those areas you may have noise, comfort or solar gain issues triple-pane is an option.

Last and least, is the basement slab, since the design water temperature for most of our basement walk-outs is now in the mid-70's range, the Delta "T" is so low that you can't begin to approach the magical 10% of load previously mentioned, even under design conditions.

These are the our minimum standards as you exceed these the ROI is a matter of shopping and personal goals; financial, personal comfort and environmental.

This post died 7 months ago...and of course you can approach a 10% downward slab heat loss... You can even approach a zero % downward slab heat loss if you use enough under-slab insulation. However, 10% is considered a reasonable target for most buildings.

The LOWER the design the water temperature, the LOWER will be downward slab heat loss for a given under-slab insulation total R-value... Yet another reason why an inefficient HR emitter (i.e., an emitter having significant R-value between the PEX and the finished floor surface) is economic stupidity...you will either need to spend more on the under-slab insulation or accept the higher forever operational cost.