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John

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Passive / green House Design
« on: March 28, 2015, 08:14:45 AM »
Hello. I am searching for information on the qualitative and practical aspects of green house design.

To be clear, there is a wealth of information on solar systems, insulation, heating systems, HVAC, etc. However I have yet to find a resource that:

1. Lists the various options and Discusses how to integrate the systems to gather in a house.
2. Discusses qualitative theory: e.g. How to calculate how many kilowatts, cfm, % humidity! etc.
3. Discusses practical aspects of system design. For example, when installing solar panels, what operating temperatures are possible, where to connect pipes to a stratification heating tank, what kind of pumps and controls are necessary, etc.

I have had several very frustration conversations with engineers who design large scale systems but large scale systems seem to have a different sort of ethos behind them. In any event, I have not found any good sources. I am ok with math and wouldn't mind even thermodynamic all calcs... Though I wouldn't trust my answers without verification.

Thanks

Neven

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Re: Passive / green House Design
« Reply #1 on: March 28, 2015, 09:34:39 AM »
Hi John, and welcome to the ASIF. I'm moving this topic to the Walking the Walk category, as it's more appropriate there and you might get more answers.
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Neven

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Re: Passive / green House Design
« Reply #2 on: March 28, 2015, 09:37:26 AM »
I'm planning on building a greenhouse as well in the near future (hopefully next year or so), and the last time I researched the subject, I came across this very informative website: Passive solar greenhouse.
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jbatteen

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Re: Passive / green House Design
« Reply #3 on: March 28, 2015, 07:17:30 PM »
What's your climate?  Have you heard of high tunnels?  They look like plastic caterpillars, with translucent sheeting over a simple half-cylinder frame.  In northern climates like Minnesota where I'm from, they add about 4 weeks in the fall and about 8 weeks in the spring.  Furthermore, they provide protection from wind and severe weather.  The University of Maine has shown them to triple to quadruple yields of raspberries per acre.  If your climate is mild enough, you can grow year round in them, probably only spring greens in the wintertime, not tomatoes or something.  That's not possible in Minnesota because it's just so cold and dark in November, December, and January.  They are heated only by the sun, and the only materials are the frame and the plastic sheeting, so they're very economical.  They typically pay for themselves after the first 2-3 years growing high value produce.  At least in my area, heated greenhouses are rarely economical.  They also require a massive up front investment.

If you have any interest in high tunnels, the University of Minnesota and the University of Maine have a lot of good reading material online.
http://hightunnels.cfans.umn.edu/
http://hightunnels.cfans.umn.edu/minnesota-high-tunnel-production-manual/
http://www.mofga.org/Publications/MaineOrganicFarmerGardener/Spring2005/Raspberries/tabid/1223/Default.aspx

Anne

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Re: Passive / green House Design
« Reply #4 on: April 05, 2015, 10:54:33 PM »
John, I'm not sure where you are on this and whether you mean green House-design (as I understand you) or greenhouse design (as others do). Assuming it's the former, I'm green in a different sense but interested in finding out more. Passivhaus is an interesting concept though I'm not sure how far it can go to help me in retrofitting. I don't even know if they are all they're cracked up to be or even remotely affordable: perhaps others can comment? I guess you've come across their site and the handbook (apologies for Amazon link!)

Neven

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Re: Passive / green House Design
« Reply #5 on: April 05, 2015, 11:29:07 PM »
Anne, a passive house is basically a super-insulated home with a heat recovery ventilation system.

Standards according to Wikipedia:

The Passivhaus standard requires that the building fulfills the following requirements:[24][25]

    The building must be designed to have an annual heating and cooling demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²
    Total primary energy (source energy for electricity, etc.) consumption (primary energy for heating, hot water and electricity) must not be more than 120 kWh/m² per year (37900 btu/ft² per year)
    The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door
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Anne

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Re: Passive / green House Design
« Reply #6 on: April 06, 2015, 12:22:33 AM »
I thought so, Neven. It's basically a case of "you can't start from here" in my situation! Is this what you have been building?

Neven

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Re: Passive / green House Design
« Reply #7 on: April 06, 2015, 01:26:50 AM »
I thought so, Neven. It's basically a case of "you can't start from here" in my situation!
Yes, it's difficult to achieve in existing buildings, because of thermal bridges etc. Not always desirable either.

Is this what you have been building?

Yes, but I didn't look too much at the standards, and I'm not interested in a certificate or anything either. Another really important aspect is user behaviour. This can compensate building imperfections.

I'm going to collect data in the coming year to see how close we are coming to passive house standards. And then we'll optimize a bit more.
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Laurent

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Re: Passive / green House Design
« Reply #8 on: April 06, 2015, 09:15:17 AM »
Well, not only a box but a building system based on bioclimatic principles :
http://greenbuildingelements.com/2011/01/13/green-building-101-using-bioclimatic-design-to-build-a-passive-sustainable-dwelling/
and mainly it is also about insulating the house against the air that may come inside, any little hole can wreck your system if you do not pay attention, like an electric plug often the air is coming from outside via the electric system.
Adding a little connecting zone before a door where you drop the shoes or what ever, etc... (off course the air inside has to be replenish, manually or a system based on hygrometry only or with thermal exchange)
« Last Edit: April 06, 2015, 09:25:48 AM by Laurent »

John

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Re: Passive / green House Design
« Reply #9 on: April 13, 2015, 01:48:09 AM »
Hi all and thanks for the replies.

I am referring to the design of a house to live in done to as green as possible standards. Apologies for the confusion.

We have an old stone house built in bits and pieces and now protected historically. It also has a shared wall with another house. The upshot of this is that while PassiveHaus design is theoretically possible in our situation, it would require, legally, a complete rebuild of the house in order to trigger the efficiency incentives that override historical concerns.

For example, our neighbor is doing that but he had to strip his house down to stone only, removing all wood beams, dirt floors, old double paned windows, etc. We have considered that route but for a variety of reasons: life situation, financial, legal, and desired finished product, we will probably go the piecemeal bit by bit reconstruction route. For example, in the piecemeal route, we can build an internal frame to 'support' existing structures and then knock down and external wall and rebuild it, enhancing it both structurally and with new insulation and gain internal space. However, to redo the whole house means all the stone walls stay as they are. I can't swear to any of this because until you actually try to get something through zoning, you have no idea what bureaucratic reality is. I think it comes down to someone being willing to take a risk on approving a bunch small non standard repairs but not a larger non standard complete project.

So this leaves us with trying to design a thermal system that works for the present but also grows as we change both the house and the thermal system. We have a sketchy radiator system now and it would be very nice to fire it up and have some evenly spaced heat. However, it requires a new boiler and the radiators are too small and missing in some rooms. I would prefer a solar system instead of a boiler for ecological reasons and personal esthetics but solar doesn't work with small radiators.... Or does it? I know of no theoretical reason why I can't heat water to 80 degrees with solar and feed the radiator system. However, I can't seem to find any good literature on the subject, nor the performance specs to connect either a low temp floor system or a high temp radiator system to a storage tank.

In talking with representatives from various boiler, solar, heat pump and pv systems, I get a lot of bologna about why I have do buy the system that their company sells. I have tried talking with engineers and the officials from local government offices that oversee public installations of thermal systems and leave their offices somehow more confused than before entering. And of course, all of this is subject to the aforementioned bureaucracy regarding construction.

So I have decided that I will design my own system. It will have components that are official such as any pv work, rooftop solar heating or boiler installation. However it will also have a homemade design to integrate the components as well as some homemade panels and so on. For example, as a starter, I would like to heat some of the basement with a ground based solar panel that feeds wall panels. None of this needs approval ( says me) because none of it will be attached to anything in the house. Leaving my personal need for a victory over bureaucracy aside, I also simply want to know the answers to my questions before I talk to engineers/salespeople about integrating their system into my house. I imagine that, for example, instead of buying a solar panel system that does or does not work well with a furnace or boiler system installed by others that does or does not work well with little radiators, etc., I have a system that has a core design (given my design capabilities) and is ready for component wise expansion. Then all I am pricing is a set of rooftop panels that plugs in, or a boiler that augments solar, etc..

I was hoping to find a book that explains things like can I use solar to heat radiators, if not why not, what design aspects I need to consider when designing solar panel systems, how to understand how storage tanks work from a system flow point of view, etc.

I am sure these books or websites exist but I haven't really found any results that are technical yet not so specific as to refer to just one tank, panel, etc.

Sorry for the long post, I am on new born baby watch and have keystrokes to spare.

J


Neven

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Re: Passive / green House Design
« Reply #10 on: April 13, 2015, 01:56:52 PM »
John, couple of questions:

- Where are you located? What's the climate like?
- How is your house positioned?
- How much square metres of windows facing which way?
- How thick are the existing walls?
- How warm do you need it to be during winter?
- Is biomass available to you, like wood or pellets?

The greenest and probably cheapest thing to do, is leave the outer walls standing. But that will leave thermal bridges, of course.

My personal opinion with regards to heating with solar hot water panels (something that was discussed in the Interesting building projects topic):

For me solar water heating was a sine qua non, also because it is heavily subsidized here. In fact, if you want a general home subsidy you will only get it if you install a solar water heating system! But when I looked into it, I saw there were some downsides to it as well. The biggest downside, as with all solar stuff, is that there's little of it during winter and during summer there's too much of it. After having looked deeper into it, I figured that putting 1 kWp of PV extra on my roof to feed an electric boiler would be cheaper and much less of a hassle than solar water heating. No plumbing, no pumps, no big panels on the roof, all of which can fail.


In the end we even decided to dump the electric boiler for a heat pump with a 300l tank attached to it, which on average consumes 2 kWh per day for all our warm water needs. Next year we'll probably add a small wood stove to it, of which 80% of the heat energy goes into water that is pumped around the 300l tank, and 20% of the heat energy goes into heating the air in the living room. This circumvents the problem of too little PV electricity production during winter, when electricity consumption is highest.

But you'll be needing a more serious heat pump to heat your house (we only heat water with it for the kitchen and bathroom), and I don't know how the costs stack up there compared to solar water heating.
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John

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Re: Passive / green House Design
« Reply #11 on: April 18, 2015, 11:09:04 PM »
Hi Nevin,

We live in the Italian Alps south of Innsbruck. (By the way, I have posted here under another name but not for sneaky reasons, just because my job, or part of my job, for for a while was researching websites anonymously and it just gets to be a habit...)  I imagine our climate is not that different from yours.

We have a two story house built on the side of a hill. The attic is still open to the elements. When this was a working farm, they would fill the attic with hay in the late fall and then gradually feed the hay to the cows and goats in the basement. The hay served as both insulation and heat as the animals ate their way through it. We still have about a half meter of hay up there, on top of a maltapaglie ceiling.

That is the first step: insulation, away with the hay and in with some sort of insulation, probably paper. The roof is tiled with cement tiles in part and porfido (a type of local rock ) for the rest. This winter, on a day when it was about freezing, the tiles were warm to the touch from the sun. This is hat triggered my interest in solar heat, or rather convinced me that it was worth trying.

I'll try and figure out stratification tanks over the next few days and hopefully talk to a local company about pv.


Neven

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Re: Passive / green House Design
« Reply #12 on: April 18, 2015, 11:29:23 PM »
We live in the Italian Alps south of Innsbruck. (By the way, I have posted here under another name but not for sneaky reasons, just because my job, or part of my job, for for a while was researching websites anonymously and it just gets to be a habit...)  I imagine our climate is not that different from yours.

Not very different probably, but we live outside of the Alps, in Austria's southeast, where it's generally warmer, especially during winter.

We have a two story house built on the side of a hill.

What is your position with regards to the Sun?

The attic is still open to the elements. When this was a working farm, they would fill the attic with hay in the late fall and then gradually feed the hay to the cows and goats in the basement. The hay served as both insulation and heat as the animals ate their way through it. We still have about a half meter of hay up there, on top of a maltapaglie ceiling.

That is the first step: insulation, away with the hay and in with some sort of insulation, probably paper.


You mean cellulose, right? That's the main insulation material we used for our house.

Will you be insulating the attic floor, or the roof directly? I would guess the first.

The roof is tiled with cement tiles in part and porfido (a type of local rock ) for the rest. This winter, on a day when it was about freezing, the tiles were warm to the touch from the sun. This is hat triggered my interest in solar heat, or rather convinced me that it was worth trying.

Be sure to ask PV companies if the panels can be installed on the kind of roof you have. The mounting materials need to go under the tiles, and if those tiles are all flat, this might be difficult to achieve. We put the wrong tiles on our roof (also flat), and so special metal tiles needed to be bought to replace the tiles where the mounting hooks were installed for the construction. All in all it cost us 1000 euros more.

I'll try and figure out stratification tanks over the next few days and hopefully talk to a local company about pv.

Good luck.
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John

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Re: Passive / green House Design
« Reply #13 on: May 21, 2015, 11:44:43 AM »
anyone know how to post an image form google sites?



The url between the image tags is:

https://docs.google.com/uc?id=0B86q15sB8c-WQ2JLYnhaQWdlM0E

« Last Edit: May 21, 2015, 01:40:20 PM by John »

John

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Re: Passive / green House Design
« Reply #14 on: May 21, 2015, 12:00:33 PM »
In any event, here is the link:  https://www.sites.google.com/site/housesvdp/photos

The house consists of two floors of stone walls and an open attic that was used to dry hay. The basement was a stall for cows, pigs, rabbits and goats.

Eventually we will close in the attic but for the moment we will lay cellulose loose fill covered with some sort of protection. "for the moment" is our operating strategy as everything is a balance between living there now and reconstructing in the future. Everything we do now risks being a waste of time and money.

Note the stone walls, visible in the openings in the attic. I figure u = 2.10 (metric units). Right now  only the first floor is habitable but at roughly 130 square meters (since it abbuts the un insulated attic of the neighbors i count all four walls), that gives a loss of circa 270 watts per degree. In the winter, at a fairly conservative 20 degree difference, that gives about 5.4 kw for the walls alone.

Right now, I estimate the u value for the ceiling/attic floor at 2.0. The composition is a thin layer (circa 2cm) of lime cement over irregularly spaced wood over an air gap or beams over a sort of adobe stucco (maltapaglie). I figure 2.0 to be conservative because it is much hotter near the ceiling than the floor but I really have no idea; it could be 3 or higher for all I know. However I am not that worried about accuracy as we will insulate this with about 15 cm cellulose, bringing the u down to about .3

Why so little? Mainly cost effectiveness. I am willing to be corrected but going from .3 to say .15 seems a lot of expense for little gain, especially when the cost can be put in to something else.

After learning a lot about stone house construction (mainly on a cell phone while in the hospital so I can't really say 'learned' maybe 'became less ignorant'), there doesn't seem to be much point in insulating the walls. The costs, in my case, are prohibative and sealing leads to problems with moisture, zoning, etc. Until we know what is going to happen to the house long term, the best results seem to be insulate the attic, eliminate leaks and find some sort of heating system.

We have put /will put in either used windows or, where we can't find a fit used, new windows and doors which, oddly enough, are not that expensive for reasonable quality (not passive hous ) pvc double glazed windows. We took the windows for the first floor from a refurbishment project for an elementary school in Austria, we have doors from a hotel redesign. I doubt we will get the u below 3.0 for any of the doors/windows but we will stop leaks and we will have nice bright windows to look out of.

We are bailing hay to stack against the lower walls, which i am told is a way around zoning restrictions but also which i doubt will make much difference in the u value anyway.

In the next post I will turn to heating considerations.



« Last Edit: May 21, 2015, 01:42:57 PM by John »

wehappyfew

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Re: Passive / green House Design
« Reply #15 on: May 21, 2015, 07:26:36 PM »
That's a daunting project, John...

I agree with most of your points.

First priority is insulating the attic, and there's no need to spend on extra insulation, as the heat loss through the walls will be much larger.

Second, seal drafts with better doors and windows.

But for your next priority, I would suggest looking at a lightweight exterior lime/perlite stucco.

- This should be acceptable to zoning regulations.
- You can add color if you want.
- It seals up any cracks in your stone walls, eliminating more drafts.
- It does not restrict moisture flow through the walls (as long as you don't use any Portland cement!)
- And, most importantly, adding about 3cm of perlite stucco should reduce your U-value from 3 to about 2. That's a big savings in your heating costs.

(this assumes your stone walls are about 50cm thick, U-value for stone = 1.5W/mK, and 0.2W/mK for perlite stucco)

You'll need to attach some kind of mesh to the wall to allow stucco thicker than about 1cm.





John

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Re: Passive / green House Design
« Reply #16 on: May 22, 2015, 06:54:51 PM »
Perlite sounds like a great idea. I rejected the idea of any sort of plastic, both for not liking plastic and for not allowing moisture to escape. I had thought about styrofoam beads but there again I didn't like the plastic. But perlite sounds like a reasonable solution. Plus it is something that I can do one wall or part of a wall at a time, which fits into my schedule.


John

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Re: Passive / green House Design
« Reply #17 on: May 22, 2015, 08:02:43 PM »
Here are the basic energy figures for the house. I am NOT at all comfortable with them having passed part of a winter in the house and having survived just fine. On the other hand, I can't seem to get them to change much.

Google sites, which I am using for photo hosting, seems to have serious problems. I include a link anyway.

https://sites.google.com/site/housesvdp/energy-calcs

Some figures:

3200 kwh  amount required to heat the domestic hot water for a year. Electricity is roughly 18 cents (Euros) per kwh.

50-58000 kwh to heat the house to comfort level all year calculated using degree days, U values. That is roughly euro 10,000 if done using electricity (which our meter would not support anyway). Is this right? I have  also used some rules of thumb (e.g. 24 kg pellets / meter square for a poorly insulated house.... times 110 meters = 2640 kg times roughly 5 kwh/kg for pellets = 13000 kwh) and gotten widely varying answers. That is a factor of 4 which makes a big difference in what our choice to heat will be.

However, it appears that solar is out as a solution. There just isn't enough heat in the winter to contribute during the time we need it most. Any solution that provides heat in the winter, e.g. a biomass stove, renders the payback period for solar ridiculous, although we have been given a 300L tank and two solar panels as a gift to use for domestic hot water heating. PV may be a solution for electricity but not until we get a new roof.

So since we have to install biomass heating Ill probably skip all the DIY work for tanks etc. While I like the idea of solar panels for heating (and there is a nice cooperative here that helps people build their own systems http://www.kosmositalia.it/) I will only do the mirrors and even that more for a project than a expectation of results.

« Last Edit: May 22, 2015, 08:48:24 PM by John »

wehappyfew

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Re: Passive / green House Design
« Reply #18 on: May 22, 2015, 09:27:44 PM »
Good work, John... making progress on your analysis.

Some more questions to help us understand your situation better:

1. Solar orientation - can't tell from your picture which way is south.
2. Yard/garden on the other side? More pictures please?
3. Ground floor use. Do you plan to make the basement/ground floor into living space, or leave it unfinished?
4. First floor means up one flight of steps, right? (In USA, first floor = ground floor)
5. Are you living there now, or do you have tenants/renters living there?
6. Window area for each wall? (north, south, east, west)
7. Foundation type and depth?
8. Floor type of ground floor? (dirt, concrete?)

I think this is a very challenging (hard) project, but worthwhile. Preserving old, well-made buildings is good, but dealing with their shortcomings is difficult.

Is your building actually well made, sound, interesting, and therefore worth preserving?

Assuming it is, you'll have to work with the strengths and weakness of old, thick stone, timber, real plaster, etc.

Strengths to enhance...

Thermal mass. If you can get some solar energy into the stone, it will hold it all night without overheating during the day. You need south facing windows, and insulation on the outside, like the perlite stucco. A dark color stucco on the south side will help a little, too. Is there room for an attached 3-season greenhouse on the south side?

Draft resistance. If you seal up any wall cracks, tighten the windows and doors, and check the ceiling for gaps and cracks (especially the wall corners), thick stone walls and massive plastered ceiling/floor timbers make comfortable homes with less cold drafts. Usually, old houses have lots of thick plaster ... build on that - don't take it out, learn the old ways, plaster it yourself.

Moisture control. Since there are no moisture barriers, your indoor humidity is self-regulated by water vapor moving into and out of the walls, wood beams, plaster, etc.  This also gives you a thermal comfort boost, as moisture releases/absorbs a lot of heat as it condenses/evaporates. Be sure you don't defeat this process with non-breathing paint, cement plasters, closed-cell foams, etc.

Weaknesses...

Cold walls in winter. This is the big problem, as I am sure you already know. Once the walls gets cold, nothing will help that cold feeling from your body losing IR heat to the walls. You have to keep pumping in more energy to feel comfortable.

Heat rises. Any gaps in your ceiling assembly will allow your money (heat) to flow out very quickly. Old houses are usually crooked, settling, shrinking, moving, and never built straight in the first place. Keeping the hot air in is a challenge. Don't forget about convection within your attic insulation - loose insulation allows rising hot air currents from below.

Water/moisture from below. I worry about the foundations and lower wall visible in your photo. Does rainwater and street runoff collect at the base of your walls? That can lead to problems.

...

I agree with Neven that the low cost of PV is making solar hot water panels obsolete. But you may not have a convenient mounting location. I would hate to spend a lot of money ruining a perfectly sound roof trying to get PV way up there. I prefer ground mounted PV.

I would think a biomass pellet stove for heat in the basement/ground floor would be cheaper than electric resistance heating, but maybe not cheaper than air-sourced heat pump (I'm assuming there's no room for ground-sourced heat pump). Something to check into. As Neven is doing (I think), grid-tied solar PV plus heat pump allows you to transfer your summer excess kWh to the grid and take them out in the winter when you need them (depending on your local utility rules).

Keep us updated so we can vicariously enjoy your hard work.




John

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Re: Passive / green House Design
« Reply #19 on: May 23, 2015, 02:56:18 PM »
Thanks for the reply.

Some more questions to help us understand your situation better:

1. Solar orientation - can't tell from your picture which way is south. See updated website pictures.https://sites.google.com/site/housesvdp/photos
2. Yard/garden on the other side? More pictures please? See updated website pictures.
3. Ground floor use. Do you plan to make the basement/ground floor into living space, or leave it unfinished? The basement/ground floor will  in the middle term be a workroom for projects, a library and a laundry room. None of these need to be heated to house levels but, picking a number, around 12 C.
4. First floor means up one flight of steps, right? (In USA, first floor = ground floor) Yes, in Italy first floor is one flight up. I am not sure that logic applies here since the house is on a hill. We use 'first floor' in the Italian sense because 'first floor' clearly isn't the basement or the attic while 'ground floor' is a bit ambiguous (not that we have ever discussed this).
5. Are you living there now, or do you have tenants/renters living there? We live here now. It is a long story. It is a house bought for love though. It is like the horrible deformed dog that comes up to you and licks your hand on a rainy night, cold and shivering, so you take it home thinking to take it to the kennel tomorrow and then somehow a year later you have a deformed dog that you wouldn't swap for the best purebred money could buy. Or so we tell ourselves.
6. Window area for each wall? (north, south, east, west) Say 4 meters per face per floor except the east face which has no windows except for openings in the attic.
7. Foundation type and depth? Half of the house is built over a cantina (complete with wine barrels, etc). The other half is a dirt floor or thin non wall-to-wall concrete slabs on dirt. I have no idea about the foundation. The soil type (I forget the name) is decently load bearing. However, the walls are built in varying stages. The oldest being 150+ years and made of partially non dressed stone (i.e. round). The upper walls are made of good flat stone. The mortar is a type of mud. Seriously. Really freaks me out so I try not to think about it until I can have time to fix it. The neighbors are all construction people and they tell me not to worry. But I do.

I think this is a very challenging (hard) project, but worthwhile. Preserving old, well-made buildings is good, but dealing with their shortcomings is difficult. ]It is a lot of fun. I love the house even if I doubt we would do this a second time, especially given the fact that this is supposed to be a weekend type project. We are further hampered by the condition that we have a policy of not spending anything on the house that we can't pay for without touching savings and without getting a mortgage. We have made the first floor livable for the two of us in three months of 18 hour days given as paternity leave. Given that we are now three (happily) we are suddenly faced with not just camping out and idly fixing this or that but having a solid well heated first floor. This changes all of our plans, perspectives, etc.

Is your building actually well made, sound, interesting, and therefore worth preserving? Ye-es, I think so. If I had done things my way, I would have built an internal frame for the house first. However: living there, new baby, zoning requirements, absurd prices of architects, .... so this is still to come. But maybe knocking it down and starting over would have been better.

Assuming it is, you'll have to work with the strengths and weakness of old, thick stone, timber, real plaster, etc.

Strengths to enhance...

Thermal mass. If you can get some solar energy into the stone, it will hold it all night without overheating during the day. You need south facing windows, and insulation on the outside, like the perlite stucco. A dark color stucco on the south side will help a little, too. Is there room for an attached 3-season greenhouse on the south side? See photos.

Draft resistance. If you seal up any wall cracks, tighten the windows and doors, and check the ceiling for gaps and cracks (especially the wall corners), thick stone walls and massive plastered ceiling/floor timbers make comfortable homes with less cold drafts. Usually, old houses have lots of thick plaster ... build on that - don't take it out, learn the old ways, plaster it yourself.

Moisture control. Since there are no moisture barriers, your indoor humidity is self-regulated by water vapor moving into and out of the walls, wood beams, plaster, etc.  This also gives you a thermal comfort boost, as moisture releases/absorbs a lot of heat as it condenses/evaporates. Be sure you don't defeat this process with non-breathing paint, cement plasters, closed-cell foams, etc. I made a mistake initially when i did a bathroom wall and used cement to repoint the stones. However I am hoping that since it is a single barrier, it will not create problems. Everything else has been very breathable - not that the old owners didn't do a fair amount of damage themselves first. But this will all come out eventually.

Weaknesses...

Cold walls in winter. This is the big problem, as I am sure you already know. Once the walls gets cold, nothing will help that cold feeling from your body losing IR heat to the walls. You have to keep pumping in more energy to feel comfortable. Yup.

Heat rises. Any gaps in your ceiling assembly will allow your money (heat) to flow out very quickly. Old houses are usually crooked, settling, shrinking, moving, and never built straight in the first place. Keeping the hot air in is a challenge. Don't forget about convection within your attic insulation - loose insulation allows rising hot air currents from below. Yup.

Water/moisture from below. I worry about the foundations and lower wall visible in your photo. Does rainwater and street runoff collect at the base of your walls? That can lead to problems. The house seems dry at the moment. Most of the outside is inclined enough that water doesn't collect and on the one side that it isn't inclined the pavement slopes away from the house. There is considerable ground water in the area, but so far there haven't been any problems.

...

I agree with Neven that the low cost of PV is making solar hot water panels obsolete. But you may not have a convenient mounting location. I would hate to spend a lot of money ruining a perfectly sound roof trying to get PV way up there. I prefer ground mounted PV. I also wanted ground mounted pv but it is a code no no except in very restricted circumstances.

I would think a biomass pellet stove for heat in the basement/ground floor would be cheaper than electric resistance heating, but maybe not cheaper than air-sourced heat pump (I'm assuming there's no room for ground-sourced heat pump). Something to check into. As Neven is doing (I think), grid-tied solar PV plus heat pump allows you to transfer your summer excess kWh to the grid and take them out in the winter when you need them (depending on your local utility rules). I agree we should look deeper into this. I had rejected it originally because the costs were too high and we are eligible for a large incentive to change our diesel boiler to pellets. I was also concerned about the costs of heating during a bad winter. However, now that we have supplemental heating in terms of a small pellet stove and a wood stove, a heat pump might work. I like the idea of being free from biomass as well. I'll do some research on this. Thanks.

Keep us updated so we can vicariously enjoy your hard work.
« Last Edit: May 25, 2015, 08:00:12 AM by John »

John

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Re: Passive / green House Design
« Reply #20 on: May 25, 2015, 10:22:15 AM »
Returning to the reasons for starting this thread, I have returned home from the hospital and the house is effing cold. Some of that is due to not having the windows or shutters open while it was hot outside. But I think at night the area still gets cold enough that any heat gained during the day is lost again. We need some way to transport heat into the core of the house. So while based on the solar numbers a pellet stove or a boiler will be needed for the winter, I return to considering pv or thermal solar panels.

PV would be my first choice if we could balance energy accounts on a yearly basis, i.e. either sell the power in the high months and then use that money to buy it back in winter or else have a winter credit for the summer. However, my understanding (which is not great since the regs are both in Italian and in bureaucratese) is that the system now in place (since 2012) is of monthly credits. So if we generate 300 kwh in June and use 100 kwh, I have to pay for the 100 kwh now but at the end of the year I get a refund of 60% of the cost for the 100 kwh. If I generate only 50 kwh in a month and use 100 kwh, I get a refund of 60% of the 50 kwh that I generated.  Any surplus generated during one month cannot be applied to other months, ie.e any summer surplus is lost.

That isn't to say that PV isn't value for money for year round usage, i.e. dishwasher, clotheswasher, power tools, hot water heating. Nor does it imply that pv + heat pump wouldn't work for a large amount of the spring and fall.

MonthJanFebMarAprMayJunJulAugSepOctNovDec
rough guess at real insolation kwh / m2 /DAY.581.051.442.062.532.623.032.522.001.29.50.43
Euro savings (pellet cost) for 10 m2 panels10.3718.9326.0137.0745.5247.1754.5345.3336.0023.188.937.72

So the total savings for the year for installing 10 m2 of thermal panels is roughly euro 360. This inlcudes a large savings during the summer months. But on the balance, I am ok with these figures mainly because I think I am underestimating insolation. The payback for an installed system (figure 4500 for the panels plus installation 2000) is pretty long.  There are incentives though, euro 370 per meter for thermal panels, if installed by a professional.

Anyway, all this returns to how to design the internals of the system, how many storage tanks (e.g. separate ones for DHW and heating, one for low temp heating and one for high temp heating.....), how to shunt excess heat, how to design for excess heat versus enough capacity in the winter. So, next time I will try for specific questions instead of overviews of the situation.

John

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Re: Passive / green House Design
« Reply #21 on: May 29, 2015, 09:47:11 AM »
Having now spent a few hours with the people from Kosmos, the thermal solar cooperative, thermal is pretty dismal for heating a house. The basic problem is that unless the house is super insulated there is not enough heat for the winter and way too much in the summer. Panels in the summer can be covered of course but the cost remains.

All this I knew but I was hoping that i was wrong in my calculations / figures. It just seemed that with the roof tiles getting so hot in the winter, if that heat was captured, it would serve to heat the basement and that heat would then rise. Evidently this isnt how it works, based on the setup they were using to heat a basement in a casaclima: 4000 L of storage, I forget how many panels, and underfloor heating all combine to heat only the room in which the system is installed.

On the positive side, at least they walked me through how storage tanks and heating systems in general work. The tricks is basically mixing valves. A stratification tank is a good idea but the stratification is not required, except for efficiency. Imagine, instead of a single tank, separate tanks: water from solar, water from a boiler, water that returns from radiators, water that returns from underfloor heating... to use these tanks, the water used for any given purpose has to be mixed in order to achieve the desired temperature. It is the mixing (and temperature controls) that makes the whole system work. And systems are not designed to work under every condition possible, at least not optimally. Engineers make calcs. based on what they think the likely operating conditions are and then optimize the system for those condition plus a grey area on either side (and engineer solutions for worst case scenarios to avoid breaking the system). So it feels good that it isn't an unknown thing, even if I probably wont be doing more than domestic hot water.


John

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Re: Passive / green House Design
« Reply #22 on: June 02, 2015, 05:36:12 AM »
Below is a link to a Washington Post article on pellets. Something to consider when considering whether to install a pellet boiler or not. I would use local pellets, as much for cost as anything else, as there is a cottage industry of using the local residue of sawmills and wood for burning. Supposedly I can get pellet costs down to .04 euros per kwh - hard to beat, but not as green (perhaps) as panels.

http://www.washingtonpost.com/national/health-science/how-europes-climate-policies-have-led-to-more-trees-cut-down-in-the-us/2015/06/01/ab1a2d9e-060e-11e5-bc72-f3e16bf50bb6_story.html

wehappyfew

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Re: Passive / green House Design
« Reply #23 on: June 19, 2015, 10:15:02 PM »
Hey John,

Here's a product you might consider using for exterior and interior plastering to improve the heat resistance of your stone walls:

https://www.diasen.com/sp/en/p/diathonite-evolution.3sp

U-value = 0.045

(for Americans, R-value = 3.2/inch)

That's pretty outstanding for a plaster/stucco.



John

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Re: Passive / green House Design
« Reply #24 on: June 22, 2015, 10:35:07 AM »
Thanks for the suggestion. It does seem like a good product, and I wrote to the company for more information. Unfortunately, it seems to come in at upwards of 40 euros per square meter. But it is hard to verify those prices. In the world of insulation, that may not be too excessive but for us, or at least for this project, it is too much. I will update here with what I find out.

John

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Re: Passive / green House Design
« Reply #25 on: June 22, 2015, 10:37:27 AM »
By the way, if anyone knows anything about just using perlite and lime mortar directly, I would appreciate suggestions, links, etc. The materials cost isn't bad but I have no idea what the u-value of the final u value would be   and for the work involved it could easily be a false economy.

ghoti

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Re: Passive / green House Design
« Reply #26 on: November 03, 2016, 10:20:43 PM »
A bit of good news: 42 unit apartment building in Ottawa, Ontario has been built to Passivehaus standards. 

http://www.metronews.ca/news/ottawa/2016/10/02/new-affordable-housing-complex-boasts-top-efficiency-rating.html

John

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Re: Passive / green House Design
« Reply #27 on: December 16, 2016, 09:27:55 AM »
To follow up: we ended up not doing much with the house. Part of that is having a baby, amazing how a baby eats up time, money and energy. In terms of renovating, making a house baby ready is a very different point of view from restoring and in the end, we decided to do that and put off energy efficiency, renewable sources for a bit.

It was not just the baby however. It was also indecision about what we wanted to do with the house and it seemed a waste to put in effort now only to want to change it a few years later. In terms of renewable energy, after looking around, it seemed that a lot of technology was changing as well as local regulations. Specifically, for our preferred system of heats pumps and electric power solar panels:

Heat Pumps: last year seemed to have a lot of new products designed for colder climates. But that technology was relatively new and expensive for the returns.

Solar Panels: e.g. systems like Solar City's tiles + batteries. Are we better waiting a few years for efficiency to go up and prices to come down?

Renovation/Upgrading and local regs: it seems to be an all or nothing proposition: if we touch the house in major ways, we have to upgrade the energy efficiency of the whole house. This is also true from a cost perspective.

What we did instead is throw sheets of load bearing mineral wool on the attic floor, put in new windows where needed and install a pellet boiler-stove.

The pellet stove plus installation including connection to the heating system, installing a chimney liner, replacing several radiators and installing thermal valves everywhere cost about 5000 euros. Aside from being the lowest cost option (important in light of our uncertainty), the government offered a rebate of 2300 euros on that model stove. We also have a wood stove in the kitchen and we get by with about 1500 euros of wood and pellets per year for a house that is comfortable albeit with cold spots.

None of this is the ideal long term solution but from an engineering standpoint, we decided we were going with 5 year usage max. I mean that if we repair, build, install something, we are shooting for a quality of design to last 5 years.  Given that constraint, this seemed the best 5 year solution.

On the other hand, 5000 kg of pellets per year is 25000 kwh roughly if I remember right. Enough to drive a small car around the world three times.

One project that still interests me, and for which I have all the material, just not the time yet, is putting in mirrors to reflect both light and heat onto the house. I think I figured that optimally, each square meter of mirror saves about 120 euros per year in heating costs, assuming Oct-April usage. At least for the first few mirrors. It is a low cost solution and experimental so I can get away with it in the five year plan budget. Similarly, I plan to roughly close in some of the car port to start trying to grow more food year around. ... when I have time : )




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Re: Passive / green House Design
« Reply #28 on: December 16, 2016, 09:51:01 AM »
Thanks for the update, John. And good luck with the house (and the baby).  :)
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Re: Passive / green House Design
« Reply #29 on: December 17, 2016, 03:29:52 AM »
If I lived in a cold climate I would want to set up a solar system and one of these residential thermal storage units.  http://www.steffes.com/off-peak-heating/room-units.html

by charging it up during the day when the sun is shining a significant amount of that extra electricity could be safely stored for later release as heat in the nighttime.
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ghoti

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Re: Passive / green House Design
« Reply #30 on: December 17, 2016, 03:56:39 AM »
Unfortunately most cold climate locations are high latitude - so very little sun during the winter. I'm not even so far north at 45N latitude and during December/January my solar thermal and solar PV systems gain roughly 10% of what they do in May June July. It is tough to store excess from summer for use in the winter. It is possible but involves amazing storage systems. I dream of being able to do this eventually.

Zythryn

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Re: Passive / green House Design
« Reply #31 on: December 17, 2016, 05:13:28 AM »
Cloudiness is a bigger issue than angle in our area.
Our array is rooftop mounted at 44 degrees.  On a sunny day, as long as the panels are clear of snow, we get about 80% of what we get in the late summer.

While that angle is not optimal for summer, it helps keep the snow off in the winter, and gives us better winter production when we need the power.

sidd

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Re: Passive / green House Design
« Reply #32 on: December 17, 2016, 07:28:07 AM »
RE: winter solar use

Solar heat panels in the midwest are often mounted vertically facing south. Avoids snow accumulation with max heat when most needed in winter.

And I have seen perfectly functioning setups which are no more than woden box with polycarb face and gardenhose coiled within, hose and interior painted black. Caution: gardenhose may melt if water circulation is too low or cold leg inadequately dumps heat ...