Green building advice for a new house I have been following this site from for a while as I have an interest in green building and particularly cost effective energy efficiency. I now suddenly find I have the opportunity to build a new house, unfortunately for the wrong reasons as we were one of the victims of the Sonoma wildfire last October. I would appreciate some advice from the considerable collective wisdom here. Background We are in the Sonoma Valley, climate zone 2 I believe. We have a very equable climate. Lows can be in the mid 20s but only for a few days a year, highs can be over a hundred but again for relatively short periods and we have enough marine influence that it cools down overnight. Historically we have only used ac for a few days a year because (partly due to house design) we can close up in the am and open up in the evening. This year was the warmest we have experienced in 12 years, maybe global warming? We will rebuild a very similar house on the same footprint. It is (was) about 2,000 sf, 3 bed 2 bath, single level, rectangular with the long side oriented SW. Had a standing seam metal roof with 11kw of solar that was just a year old; when I get to it I can check the true up which pretty much zeroed out our electricity bill. The house had gas fired forced air heat, electric hot water tank about 3 years old. We had one EV but I can see two in the future as batteries improve. We have natural gas service. The House was designed in an African plantation style and had a 10’ overhang above a verandah wrapping all four sides. The House was 20 years old and had what must have been custom windows, no doubt expensive but sealed very badly. French doors on the SW also leaked like crazy. The previous owner had a degree in theater lighting so we probably had 100 holes in the ceiling for small recessed lights. Ceilings in the great room and all bed rooms were vaulted. Insulation was probably typical for a 20year old house, batts in walls, under floor and above the ceiling. Proposed Pretty much same again. Same footprint, same overhangs and verandah. Previously was suspended floor with crawl space but this time we will have a solid slab. High ceilings in great room and master only. I am thinking on demand hot water, either gas or electric. My inclination is to go for good insulation without going crazy, my sense is that in our climate insulation is a lot less critical than it is for most folks. But what does ‘good’ mean? I want a big emphasis on air tightness as the key element of the construction. Presumably I should insist on a blower door test, what criteria for this would be reasonable? Should we insulate the slab? If so how much and how do we detail the edge conditions? The vaulted ceilings in great room and master will still leave attic space above due to the high roof line. Do we insulate above the ceiling? Ducts will then run in unconditioned space which is not ideal. But is sealing under the roof worth the effort? How do we deal with moisture issues? HVAC? Forced air again? I am thinking I need a consultant to do Schedule J and D. Thinking radiant heat in the bathrooms? What about ventilation? I was originally thinking HRV but it’s probably not cost effective given the low heating / cooling needs. Can you get a furnace with a fan that will run efficiently and circulate air using the ducts? We also intend to incorporate grey water and rain water harvesting. I have always been a little dubious about the latter in our Mediterranean climate where the usefulness comes down to how much storage you have. However we have we have the opportunity to create tank / cistern in concrete under the front verandah that could give us 10,000 gallons gravity fed, hopefully at a reasonable cost. I have been recommended to use casement Marvin Integrity windows and French doors as a good value for money efficient window. Thoughts on this? We are in a Wildland Urban Interface zone ( I actually would have said before October that was an incorrect designation.... ) so will need to provide fire resistance on the exterior which could be Sheetrock under the board and batt siding. I am thinking Hardieplank as a better alternative? We also need to sprinkle per current Ca codes. We are on well and I thought we would need a lot of storage for the sprinklers and away of pressurizing the system. The fire marshal says he only wants 300 gallons which we can do from our domestic system unless it needs to be segregated ( he didn’t say so). We also will rebuild a 1,000 sf second unit. I bed 1 bath reusing the existing slab which is deemed to be ok. It will have a common wall with the main house garage. Because the bedroom will open onto the main living area I am thinking mini splits with supplemental heat in the bathroom. Good idea? How many units would I be likely to need. What sort of additional heat in the bath? Budget will be tight on this unit, so probably not radiant. Reusing the slab means no effective way for slab insulation I assume. What else should I be thinking of?? Sorry for the meg they post but so much to think about. All iinput will be appreciated. Thanks in advance.

I would recommend breaking up your post into easier to read questions. There is a lot to read there without paragraphs and actual outlined questions.

My first thought on a home that burned in a wildfire is FIREPROOFING the next home. What would be the point of building another home only to have it burn down again? I would recommend ICF concrete walls with a steel roof. Fire resistant stucco applied to the outside and defensible space around the home.

In a climate like yours, ICF works great in insulating and of course provides a fire resistant structure. No exposed wood on the outside. Cover all fascias and overhangs with steel cladding.

Posted By Robt on 09 Feb 2018 12:52 AM

Green building advice for a new house

I have been following this site from for a while as I have an interest in green building and particularly cost effective energy efficiency. I now suddenly find I have the opportunity to build a new house, unfortunately for the wrong reasons as we were one of the victims of the Sonoma wildfire last October. I would appreciate some advice from the considerable collective wisdom here.

Background:

• We are in the Sonoma Valley, climate zone 2 I believe.
• We have a very equable climate.
• Lows can be in the mid 20s but only for a few days a year, highs can be over a hundred but again for relatively short periods and we have enough marine influence that it cools down overnight.
• Historically we have only used ac for a few days a year because (partly due to house design) we can close up in the am and open up in the evening.
• This year was the warmest we have experienced in 12 years, maybe global warming? We will rebuild a very similar house on the same footprint.
• It is (was) about 2,000 sf, 3 bed 2 bath, single level, rectangular with the long side oriented SW.
• Had a standing seam metal roof with 11kw of solar that was just a year old; when I get to it I can check the true up which pretty much zeroed out our electricity bill.
• The house had gas fired forced air heat, electric hot water tank about 3 years old.
• We had one EV but I can see two in the future as batteries improve.
• We have natural gas service.
• The House was designed in an African plantation style and had a 10’ overhang above a verandah wrapping all four sides.
• The House was 20 years old and had what must have been custom windows, no doubt expensive but sealed very badly.
• French doors on the SW also leaked like crazy.
• The previous owner had a degree in theater lighting so we probably had 100 holes in the ceiling for small recessed lights.
• Ceilings in the great room and all bed rooms were vaulted.
• Insulation was probably typical for a 20year old house, batts in walls, under floor and above the ceiling.

Proposed: Pretty much same again.

• Same footprint, same overhangs and verandah.
• Previously was suspended floor with crawl space but this time we will have a solid slab.
• High ceilings in great room and master only.
• I am thinking on demand hot water, either gas or electric.
• My inclination is to go for good insulation without going crazy, my sense is that in our climate insulation is a lot less critical than it is for most folks.

But what does ‘good’ mean? I want a big emphasis on air tightness as the key element of the construction.

Presumably I should insist on a blower door test, what criteria for this would be reasonable? Should we insulate the slab? If so how much and how do we detail the edge conditions? The vaulted ceilings in great room and master will still leave attic space above due to the high roof line.

Do we insulate above the ceiling? Ducts will then run in unconditioned space which is not ideal.

But is sealing under the roof worth the effort? How do we deal with moisture issues? HVAC? Forced air again? I am thinking I need a consultant to do

Schedule J and D.

Thinking radiant heat in the bathrooms? What about ventilation? I was originally thinking HRV but it’s probably not cost effective given the low heating / cooling needs.

Can you get a furnace with a fan that will run efficiently and circulate air using the ducts? We also intend to incorporate grey water and rain water harvesting.

I have always been a little dubious about the latter in our Mediterranean climate where the usefulness comes down to how much storage you have.

However we have we have the opportunity to create tank / cistern in concrete under the front verandah that could give us 10,000 gallons gravity fed, hopefully at a reasonable cost.

I have been recommended to use casement Marvin Integrity windows and French doors as a good value for money efficient window.

Thoughts on this?

We are in a Wildland Urban Interface zone ( I actually would have said before October that was an incorrect designation.... ) so will need to provide fire resistance on the exterior which could be Sheetrock under the board and batt siding.

I am thinking Hardieplank as a better alternative? We also need to sprinkle per current Ca codes. We are on well and I thought we would need a lot of storage for the sprinklers and away of pressurizing the system. The fire marshal says he only wants 300 gallons which we can do from our domestic system unless it needs to be segregated ( he didn’t say so).

We also will rebuild a 1,000 sf second unit. I bed 1 bath reusing the existing slab which is deemed to be ok. It will have a common wall with the main house garage.

Because the bedroom will open onto the main living area I am thinking mini splits with supplemental heat in the bathroom. Good idea? How many units would I be likely to need.

What sort of additional heat in the bath? Budget will be tight on this unit, so probably not radiant. Reusing the slab means no effective way for slab insulation I assume.

What else should I be thinking of??

Sorry for the meg they post but so much to think about. All input will be appreciated. Thanks in advance.

Repaginated for better readability.

Thanks dilettante. Looks readable now!
Because it was so long I composed it then pasted it and all the paras.....
Hopefully, thanks to my copy editor I will now be the beneficiary of some of the excellent advice form this site
R

Thanks dilettante. Looks readable now!
Because it was so long I composed it then pasted it and all the paras.....
Hopefully, thanks to my copy editor I will now be the beneficiary of some of the excellent advice form this site
R

The software version this site uses sucks and depending on what browser you use will decide how it shows up. The old timers know this but still bitch at people like it is their fault instead of helping. Sorry about that but welcome to the forum.

Also sorry to hear about your house. ICF and radiant floors are great options for a house but add lots of time to the build. I would think you would be in a hurry to get it done. Good luck.

I would be curious where the fire resistance weaknesses were in the previous house and plan to address them in the new house. Eliminating the crawl space with a slab would be one. There was a recent thread on this subject:

Is there an ICF block that doesn't melt or burn in a forest or house fire?

If you will be pouring a slab floor consider embedding PEX tube in it for hydronic radiant. Even if you don’t use HR in all the rooms immediately, you or someone else might want to in the future and this is the opportunity to provision for it at a very low cost.

If you are building a well sealed home, you will need ventilation which is totally different/independent of heating and a HRV is a good way to accomplish that.

Hardie Board can be accomplished in a board and batten style on ICF or stick built.

Thanks for the feedback. I am working on my paragraphing skills.

As to sailawayrb’s question re fire resistance weaknesses:
We were called by our neighbor at midnight and evacuated with horses and dogs at 12.30.
The second unit / garage went around 2.30. That was no brainer, lots of wisteria and other vegetation that shouldn’t have been there (but that the tenant liked....)
The House was still there at first light when the fire had passed through but embers were obviously still flying in the high winds. I have photos from a neighbor that showed where the fire started. Recap: the house had a metal roof, 10’ overhang and flag stone deck all around. There was only one thing on that area of the deck that was flammable, a hammock. I am sure an ember hit the hammock, flames went up the posts and ignited the wood under the overhang.
We were unlucky with the house but very lucky with the barn. It had good defensible space but charred areas around it. Also a rodents charred body was inside 2’ away from the hay. There are many examples of the apparently random nature of the fire with one building standing and the rest of the street destroyed.
A final thought on the fire. I see now that there is big difference between reducing fire exposure, for example so you can get out and to slow the spread vs having a useable structure after wards. The intensity of the heat popped the rebar in the slab under the rear deck and we have pulled it all out. I wonder what condition ICF would be in? My guess in our fire it would be standing but have no integrity.

Back to the rebuild. I was interested in ICF but had to pass, time is a major constraint and we had to move forward.
Radiant floors definitely appeal and I will investigate further. However our other constraint is budget and I assume radiant will be quite a bit more expensive as we would still have to provide air and ducting for ac. Interesting thought about putting Pex in any way.

I would appreciate any more thoughts.

Wait. Time is a constraint...but you're passing on ICF?

I fail to see how it's any slower in the long run than a standard formed concrete or stick build.

Yes, initial setup takes a bit longer and requires consideration. But once the pours begin, entire floors go together in a day.

Yes, passing on ICF with some regret. I have been attracted to ICF for a while but this is not the time.
The constraint is finding the right team to execute when we are going flat out to get our plans in before the whole world shows up at the County. Also it raises a question as to how familiar the County inspectors with ICF, in my experience any unfamiliarity = more time. Finally, as you can see from my long list of issues we have a lot of other decisions to make.