Can you build a "green" house in the Adirondacks?

[montcalm]

I did look at the code and it said R30, however it said less is okay as long as you fill the joist cavity with a minimum of R19. So, iif you have a 2x8 floor with filled cavity thats R22? and meets code if I read it correctly. That said, I support having more.

Guess it depends on what you use. Wool and fiberglass are a little different as I'm reading.

What prompted me to this is the code for a 2x6 wall with wool meets the R23 cavity, I believe. With fiberglass they call it R20.

Effectively we know this will be lower. I think any stick wall exposed to outside air should have continuous to prevent thermal bridging across the structure members.

[montcalm]

So I know this whole pier thing is a diversion, but I'm interested because I was thinking (for a camp) of doing a combination foundation, that is using piers for my living and bunk space, and then just putting a small section of either crawl space or full basement under my sink, toilet and shower. The idea there would be to run a small, propane (probably) space heater to keep the pipes from freezing during the winter, but primarily use the wood stove to heat the place for overnight winter use. It also gives a space for utility appliances to live.

The motivation here is cost. Excavation and basements are expensive. For a home, yeah I want it. For a camp, completely unnecessary IMO.

I'm also looking at moving total sq. ft. to 600 sq. ft. with dual loft.


I think the notion of "green" is quite drifted here, but due to these code requirements, the building has to be pretty darn efficient just to be legal.

[chairrock]

So I know this whole pier thing is a diversion, but I'm interested because I was thinking (for a camp) of doing a combination foundation, that is using piers for my living and bunk space, and then just putting a small section of either crawl space or full basement under my sink, toilet and shower. The idea there would be to run a small, propane (probably) space heater to keep the pipes from freezing during the winter, but primarily use the wood stove to heat the place for overnight winter use. It also gives a space for utility appliances to live.

The motivation here is cost. Excavation and basements are expensive. For a home, yeah I want it. For a camp, completely unnecessary IMO.

I'm also looking at moving total sq. ft. to 600 sq. ft. with dual loft.


I think the notion of "green" is quite drifted here, but due to these code requirements, the building has to pretty darn efficient just to be legal.

For a seasonal camp I would think about designing the plumbing so that you could drain it by opening a few valves. We have 2 camps and both are winterized by opening a few valves and pouring a small amount of "Pink Stuff" into each sink trap and toilet bowl. The feed pipes are all installed so gravity drains them...no need for heat..We never have a problem with pipes freezing if the pipes are kept inside the envelope .

[montcalm]

For a seasonal camp I would think about designing the plumbing so that you could drain it by opening a few valves. We have 2 camps and both are winterized by opening a few valves and pouring a small amount of "Pink Stuff" into each sink trap and toilet bowl. The feed pipes are all installed so gravity drains them...no need for heat..We never have a problem with pipes freezing if the pipes are kept inside the envelope .

Gotcha - yeah, we used to do our 3 season camp like this.

I have to be able to use it in the winter for it to be feasible for me. I can tolerate winter overnights without running water, but it does get old, and my wife will likely tire of it.


When I initially thought I wanted a place in the hills of my own after my family sold theirs I had really wanted to do something like the "hunting and fishing cabin" per the APA requirements. No septic, just an outhouse or compost toilet. Freeze-proof, hand-pump well. Propane and wood with some solar for lights and pumps, maybe fridge. That was my "off-grid" dream then - I looked at all sorts of modular and manufactured log cabins, etc... I finally decided it was cheaper to stay at hotels in the winter and do backpack and canoe trips with a week or two at campgrounds throughout the rest of the year. The only issue with this is there is no equity. If I had done a "cabin" 15 years ago, I'd still have it likely and could be using it with my kids right now.

I feel like I go down this dark road every few years and try to come up with some kind of "5 year plan". Bottom line is I really just want to be closer to the mountains. How that actually happens is somewhat irrelevant.

[montcalm]

WTBS though, I think if you want to build a home you should read through this thread and build a beautiful, efficient, net-zero house, if you can afford it.

[John H Swanson]

I've been building this spreadsheet model to evaluate heat loss of a house design and use it as a tool to evaluate the differences in construction options we've been discussing. This post is to share what I learned. I welcome input and corrections.

I started with this construction:

• 20x60 house footprint with a full basement
• Walls: 2x6 frame single wall on 24" centers with 2" outer polyisocyanurate insulation (R19+14)
• Ceiling: 2x8 joist flat ceiling with 16" insulation
• Windows: Qty 128 sq ft; Double pain with a U value of 0.3
• Doors: Qty 2; U value of 0.2
• Floor: 2x8 joist with R19 insulation
• Basement: 2 feet exposed; 12" concrete block with 4" of strofoam insulation on the outside (R20)
• Infiltration assumed to be 0.5 air changes per hour.

I then placed the house in either Rochester or in the Adirondacks. Climate data was known for Rochester (99% design conditions 1F; heating degree days 6738) and estimated for the the Adirondacks (99% design conditions -20F, and heating degree days 8300) using data from Burlington, VT and Glasglow, MT. I should note this is 1981 data, but its and input parameter.

The inside conditions were assumed to be 67F in the house and 50F in the heated basement.

Here's what the model showed:

Heat Loss btu per hour at design conditions
Walls:3336, 14.4%
Ceiling:2224, 9.6%
Windows:3336, 14.4% (yes the same as walls)
Doors: 731, 3.2%
Floor 970, 4.3%
Basement 4445, 19.6%
Infiltration (Sensible): 7517, 32.6%
Infitration (Latent):530, 2.3%
Total: 23197

Base design annual heat loss:
Rochester: 43.2 MM btus
Adirondacks: 53.1 MM btus
This is not the heating bill as it does not account for heating system efficiency.

I then changed specific parameters to see the related change in heating requirement:

Changing to a double wall 2x4 on 16" centers with 5.5" between the walls and +R7 outside:

• reduced wall heat loss from 3336 btu/hr to 2273 btu/hr.
• annual heating was Rochester: 41.2MM btu and Adirondacks: 50.7MM btu
• 4.6% savings

Changed to same double wall above but with +R14 outside:

• reduced wall heat loss was 1983 btu/hr
• annual heating was Rochester: 40.7MM and Adirondacks: 50.0MM btu
• 5.8% savings compared to base design

Revert to 2x6 walls and change windows to all windows 50% shaded with R7:

• reduced window heat loss from 3336btu/hr to 1668 btu/hr.
• Annual heat loss was Rochester: 40.1MM btu and Adirondacks: 49.3MM btu
• 7.2% savings

Again with 2x6 walls, Change infitration from 0.5 air changes per hour to 0.3 air changes per hour.

• Sensible heat loss went from 7615 to 6013 btu/hr and
• Latent went from 530 to 424 btu/hr.
• Annual heat loss Rochester: 40.2MM and Adirondacks 49.4MM
• 6.9% savings

I did not look at the basement but would as there is nearly 20% of the heat loss from the basement. Also note that I know there is a double counting of loss since the model counts the loss from the building floor which goes into the basement. I could take this out of the equation, but it causes issues when you put in a lower basement temperature (say 30F) as the basement losses go very low but the heat is "pouring" thru the building floor to the basement. It is easy to resolve for a house on posts.

Next step would be to convert energy savings to $ and compare to cost of implementing the construction changes. Then one can pick and choose the designed changes and put them all together into the model to see the overall impact. I probably wont do that.

I can evaluate other changes to the construction if requested.

[montcalm]

Looks great John. I'll check over later.

PS - send me a copy of the spreadsheet if you would.

[montcalm]

So John, I assume your infiltration is not via a HEX? This is just unheated air changes? If so, adding that 70% efficiency HEX could be a really big boost.


I would have set everything up based on comparison to code baseline, both option 1 and 2 for region 6. But hey, I'm not paying you, so investigate however you like



I have moral qualms about which rigid foam insulation is the best. As I see it polyisocyanurate is not very great, but some people give it good marks for eco-friendly. It's a thermoset, so it can't be recycled, only downcycled. XPS is a thermoplastic, from everything I can understand, which means it's very easy to actually recycle. There are other things to consider, like how much energy goes into the production, but for me, reducing thermoset use is a pretty obvious one.

[montcalm]

One other thing regarding the basement in the model. I think, if you insulate the basement, it's going to stay very close to the rest of the house temp at steady state i.e. once the house is up to it's steady state temp and we are regulating it via a control system. I think you'll have a small dT through the floor and probably a slight gradient wrt height if you don't have some kind of fan mixing it, but I think you could probably assume it's going to settle out a couple degrees lower.

When you look at the dynamics of heating the house up from outside temp, it sure will have a lot of heat flow as you stabilize the temps.

Right now, I think you'd have to look and see if the heat gained from the upstairs = the heat lost. If those are not equal, the temp in the basement will rise and we are no longer at steady state. Once we reach an equal energy flow between what's entering and what's leaving do we get steady state conditions. It's not explicitly stated in your model, but all the heat that is leaving the entire building we're adding back in via our heating system, otherwise our temps drop, and then heat flow changes and we are in a dynamic situation.

[John H Swanson]

So John, I assume your infiltration is not via a HEX? This is just unheated air changes? If so, adding that 70% efficiency HEX could be a really big boost.


I would have set everything up based on comparison to code baseline, both option 1 and 2 for region 6. But hey, I'm not paying you, so investigate however you like



I have moral qualms about which rigid foam insulation is the best. As I see it polyisocyanurate is not very great, but some people give it good marks for eco-friendly. It's a thermoset, so it can't be recycled, only downcycled. XPS is a thermoplastic, from everything I can understand, which means it's very easy to actually recycle. There are other things to consider, like how much energy goes into the production, but for me, reducing thermoset use is a pretty obvious one.

I used polyisocyanurate as it is R7 per inch compared to XPS which is R5 per inch ifrc. I'm not sure how they compare btus saved per $ capital. I prefer the performance but in general I recall it being pricy. I did use XPS for the basement insulation. Eco friendly is a consideration I'll make before entering a real project. It's easy enough to change in the model.

[montcalm]

I used polyisocyanurate as it is R7 per inch compared to XPS which is R5 per inch ifrc. I'm not sure how they compare btus saved per $ capital. I prefer the performance but in general I recall it being pricy. I did use XPS for the basement insulation. Eco friendly is a consideration I'll make before entering a real project. It's easy enough to change in the model.

Hey - I'm not knocking you. Just putting options out there. Without going down an extensive rabbit hole I'm not even really sure which is better, I see conflicting arguments.


Also I did read a little that there are issues with polyisocyanurate in cold environments. It apparently loses R value with temperature at a significant rate. Apparently as it cools, the R value is almost the same as XPS.

https://web.ornl.gov/sci/buildings/2016/docs/presentations/principles/principles-01/Principles01_Paper159_Letts.pdf

[John H Swanson]

One other thing regarding the basement in the model. I think, if you insulate the basement, it's going to stay very close to the rest of the house temp at steady state i.e. once the house is up to it's steady state temp and we are regulating it via a control system. I think you'll have a small dT through the floor and probably a slight gradient wrt height if you don't have some kind of fan mixing it, but I think you could probably assume it's going to settle out a couple degrees lower.

When you look at the dynamics of heating the house up from outside temp, it sure will have a lot of heat flow as you stabilize the temps.

Right now, I think you'd have to look and see if the heat gained from the upstairs = the heat lost. If those are not equal, the temp in the basement will rise and we are no longer at steady state. Once we reach an equal energy flow between what's entering and what's leaving do we get steady state conditions. It's not explicitly stated in your model, but all the heat that is leaving the entire building we're adding back in via our heating system, otherwise our temps drop, and then heat flow changes and we are in a dynamic situation.

I was thinking similar thoughts. So I (previously) considered the heat transfer equations for the heat flow from the warm to cold areas. There is a separate section in the handbook that specifically addresses the temperature in an unheated crawlspace. I did not review that section. I went with the basement. If you assume the heat entering the basement is only from the house and there is no heat added from the furnace, boiler, heating ducts etc, then you can calculate the temperature of the basement based on the heat gained from the house vs. the heat lost to the soil. This is house design (floor R19 and basement wall +R20 and basement floor) dependant. I wrote out the equations and did the algebra and voila. I have an equation that tells me the theoretical temperature of an unheated basement. I'm sure I took lots of liberty here and probably violated the groundrules of some of the formulae assumptions but I'm enjoying the journey. Anyway, the basement is warmer than outside but not by much. If your basement is warmer, as mine is, than it's because of all the other heat that is being added. I'm sure the ground heat helps too.

And here is what I found. Drumroll.....

Tbasement =(57 x T inside house +99.9 x T outside - 1235)/157.2

So at 20F I'd expect the basement to be 29F
At -20F I'd expect 3.7F

For those who doubt me I cite my experience where I stayed at a farmhouse and it was -35F outside and the hall outside my heated room was -15F. No ground heat there though.

[John H Swanson]

So John, I assume your infiltration is not via a HEX? This is just unheated air changes? If so, adding that 70% efficiency HEX could be a really big boost.

I think this is the one area that lacks significant reference to this analysis.

I just assumed that regular leaky houses are about 1.0 air change per hour.
Tighter houses are 0.5 air change per hour as is without a HEX.

It would be great for someone to research actual values measured with different construction methods to understand the potential savings.

Then, if you can get say 0.2 per hour you can bump it up to 0.5 with a HEX for improved air quality without all the heat loss.

But if the best we can do is 0.5 then.....

[montcalm]

It would be great for someone to research actual values measured with different construction methods to understand the potential savings.

I bet there are. No idea what our state DOE projects have been, but man I would love to head up a research project building houses in different regions and measuring them for a few years. Would be great to do as a partnership with actual homeowners who are doing new builds - give them some tax credit for making the data public.

Power companies I'm 110% sure are doing this, but they don't know all the specifics of each house. They know large scale trends and usage.

I have a long-winded response to this and how I saw things run in the Automotive world in response to government regulation and fuel prices. But long and the short of it, those two things drove everything.

[montcalm]

Best bet to look for any past government research from the state is to look here:

https://www.nyserda.ny.gov/

If you live in NY, there are so many incentives. Many of them are through local energy suppliers. I've been sifting through this myself trying to see what makes sense. Unfortunately a lot of this info you need to go through an installer to get, especially pricing info, which makes it a PITA to shop around. The technical details of the systems are not exceedingly advertised either on company websites. Your left with a number like SEER, which is great I guess, but it's some peak efficiency that may not be achievable under your operating conditions. It reminds me very much of fuel mileage ratings for vehicles.