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Planning for a new green home

Posted by b_valancy (My Page) on
Tue, Jan 7, 14 at 17:20

I am in the planning stages of building a new home and want to incorporate smart, efficient and cost-effective solutions into our build. I have spent hours reading blogs and information sites on various green systems- it�s all so very overwhelming! I have a good, general overview of most technologies, but I still need to get a better grasp on the "science & calculations" of everything. For example, I don�t want to install something that ends up being less than the load requirement.

I have attached a copy of the current plan for reference, approximately 2500sq feet, slab- no basement, southern exposure. Building in central Saskatchewan where the temperature has recently dropped to -40*C on days, and has stayed for an extended period at -20 and below levels. Summers can also be scorching at +35*C.

Geothermal/In Floor Radiant Heat-
I was interested in this at first as we are building on a slab, and I have heard this type of heat is amazingly comfortable. However, I am really torn when it comes to the issue of flooring. I do not want a finished concrete floor; it is hard and unforgiving; though I do realize it is the best for heat transfer. I also realize that it is a great thermal mass when it comes to passive solar heat. I would like to have hardwood, but am extremely worried about drying and warping, and worry that I could ever find a suitable product that could resist that damage.

The upfront price of a full geothermal/in-floor radiant system also has some sticker shock. There are other systems I want to implement, so I don�t want to max out the budget on this.

Passive House/Extreme Insulated and Air Tight Enclosure/Passive Solar Energy
The idea of an extremely air tight/insulated house and utilizing southern exposure in the winter seems like a no brainer to me. I am envious of the Passivhaus certified homes that completely rely on passive solar energy for their heat source. Though I want to build according to their ideas, I don�t plan on pursuing certification.

I am planning to build with an ICF structure for the walls; it is a building practice that is slowly becoming more common in our area. I am curious as to how the deeper window will affect the solar gain in the winter, if it will restrict it or not.

I have many large south facing windows on the house, maximizing sunlight and solar energy. I want to incorporate a large overhang to completely shade the house in summer. I am still searching for a website/tool on the internet that would give calculations to use for overhang and window level based on site latitude.

The northern exposure of the house will be partially blocked by the mass of the garage, and there will be smaller, more minimal windows to decrease heat loss. The lot is also across the street from a full block-sized park, with many trees that should help block cold north winter winds.

I am concerned that maybe my house is a bit large and spread out to properly utilize passive solar principles. I have read that a more compact design is ideal when planning for this purpose. I do have large south windows in all rooms on that side of the house to offset that.

I was wondering if anyone has any suggestions for brands of windows/doors to use? The only Passivhaus certified manufacturer in Canada is the Northwin and their Vision line from ���out in British Columbia.

I am going to incorporate an efficient, wood burning stove as a complementary heating source centrally located (for those days that it is -40 or cloudy). I have read that in passive houses the temperature can differ greatly between rooms several degrees. For the north facing rooms, specifically the play room/entry/kitchen this could be an issue.

There are debates on certain forums of the overheating effect of passive houses. I don�t mind being an active participant in my house (ex, opening windows at night to cool off house, closing the blinds to keep the hot summer sun out, seems like common sense). Though some Passivhaus idealists would say you shouldn�t have to open your windows if you have a proper mechanical ventilation system. Smart landscaping can also reduce overheating, deciduous shades trees blocking sun/heat in summer, allowing warm solar rays in winter.

The house has to breathe�.With any extremely air tight/insulated home, an air ventilation/circulation system is a must to keep clean air and deal with moisture/humidity issues. I am interested also in an ERV, with an air-to-air heat pump exchanger. Also want to use a simplified geothermal loop in a trench around the house with a water-to-air heat exchanger to heat/cool the outside air being exchanged. Though I do need to investigate more on this�

It is my goal to avoid installing a natural gas line into the house. I am really hoping I can plan properly and be without the standard forced air, natural gas system that is so prevalent in our area. I think most people will think we are nuts, but they will be the ones paying ridiculous energy bills every winter while we don�t. Unfortunately the SO is also the one person I will have to convince about all my green ideas.

Green/Living Roof
I found a great section on Houzz with all sorts of articles and ideabooks about "green". One that particularly caught my eye was a green or living roof system. The insulation factor of these roof systems really made me pay attention. In the summer they will block the hot sun so well, without passing the heat on to the attic or house. In winter, the vegetation helps trap snow which has its own insulating property.

There are a number of things to consider before I would install or proceed with this in the plan.
1. A flat roof or gently sloped roof is best.
When I first started sourcing ideas for this house, I had a very clear look for the house. I am partial to the craftsman style, and a lower profile roofline. Nothing with high, soaring peaks. Now, to incorporate a flat roof, I am afraid my house is going to look overly modern, when I have a more traditional style. I know there are other design elements to give that style, but I am still struggling to create a roof outline that doesn�t make the elevation of the house look unbalanced or disjointed. And a consideration is the extra load associated with this roof system. Reinforcing or special engineering may be an issue.
2. Installation and Cost
I am interested in an extensive, modular system (LiveRoof). I don�t need a garden on my roof, I have enough lot space for that, and I don�t want the hassle of starting and growing plants. Pre-grown and ready to install would be wonderful. But the only supplier of the LiveRoof system in my province is from Calgary, Alberta! It�s a lot more difficult to deal with contractors when they originate over 6 hours away. Information on the web estimates the installation to cost anywhere from $10-$25/sq ft; compared to $6/sq ft asphalt shingles. But the expected life of a green roof far exceeds an asphalt roof, due to the fact that UV rays don�t penetrate and breakdown the waterproof membrane as with shingles (plant absorb/block). It sounds like these modular vegetative trays are fairly new, so there isn�t 50-60 years� worth of proof to show these systems hold up as long as they claim.
3. Water Proof/Leaks
The argument most would make is that a person is just asking for trouble with a roof such as this. But leaks can happen with any roof that isn�t properly sealed and protected. With the modular trays, they advertise that you can lift up the panels you need to work under and replace them. Fixing anything on the roof would be more accessible in the way that it is flat and a lot safer to work on than a sloped roof.
4. Water Collection System
If the whole roof is a green roof, it will help to absorb excessive rainfall during a downpour/storm system that could lead to property flooding. In the same sense, it will also hold rain that may be have been diverted to rain barrel storage for irrigation of my regular garden/plants.

Electricity Needs
With much of the continent experiencing this polar vortex and some areas grappling with power outages for days, it really reinforces my belief that building a forever home that can sustain its power requirements and heat requirements to such an important thing. While I could get away with no furnace due to passive solar heat and a wood stove, it would be inconvenient to be without power. I am open to the idea of solar panels, but because of the high cost of solar panels, the general advice on the internet is to try and be green in other ways first. If we didn�t install them right away, I would want to leave the option in place for that to happen down the road. It would sure be nice to have credits on our power bills back from the power company if we were to sell our excess energy to them. I read a thread on the building homes forum of what to include in your new build, and someone mentioned having a tie in to the electrical panel for a generator in the event of power outage. I don�t know how much something like this would cost.

I think these on demand hot water heaters are fascinating; freeing up so much space with wall hung units, and saving power by not constantly heating and reheating water compared to a standard storage tank. I think I would have 2 separate units, one for the master bath which is further away from the rest of the plumbing, and one central to the laundry, kitchen, and second washroom. I would have to do some figuring to see if that one central heater would be enough for the load required. I don�t want to upgrade to a large gas fired one, so it could end up being a total of 3 units.

I had allocated so much room to my mechanical room, but so many of these green solutions take up less space than conventional heating/cooling systems and equipment. I may end up with more of a storage room than a mechanical room.

Skylights, Solar tubs
An earlier version of this plan had skylights and solar tubes everywhere. I definitely scaled back once I started to consider a green roof, overheating in summer, and then I knocked down a wall that created a long, dark hallway to the master bedroom. I think these still could be included, as I have in the entry and secondary bathroom; the skylights would have to have a protective coating to limit the heat radiation into the house. As a second option for the entry skylight, I thought that clerestory windows above the door would help bring light into the entry.

Thanks for any thoughts or suggestions; I know this post was long winded, and that I am by no means an expert and may have used some terms incorrectly. I definitely will utilize expert advice before I move forward with this project. Just writing this has helped sort out all the ideas running around in my head, and I can always reference back to this thread if I happen to misplace my hardcopy.


Follow-Up Postings:

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RE: Planning for a new green home

I am envious of the Passivhaus certified homes that completely rely on passive solar energy for their heat source.

This is a myth. Passivhaus does not require that only passive solar energy is used. Many Passivhaus homes have heating systems, ours has a geothermal system.

While your windows should be highly efficient, you don't have to only look at Passivhaus certified windows. The certification process can be expensive for the manufacturer. The manufacturer we used has Passivhaus certification on some of their lines, but not the line we used.


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RE: Planning for a new green home

Let me give you a few thoughts.

We went geothermal but didn't do radiant heat...we use air ducts as we are able to use it for both heat and a/c and we use it for fresh air recirc and we have ducts near our wood stove so we can circulate the heat throughout the house. This also allowed us to use softer flooring than concrete or tile.

Rather than a green roof with potential difficulties, I would opt for active solar panels which will offset the cost of electricity to run the geothermal.

Sola tubes are more efficient and less likely to leak than skylights so we put them in interior spaces.

Angled glass can be the problem with passive solar as it captures so much heat from the sun, it's like a furnace, yet once the sun goes down the glass leaks heat like crazy. So, IMO, the only way to do it is to devote space to heat generation as they are not comfortable places to live in. So we chose to do solar tempered with just gaining heat in the winter from the sun.

We have 2 tankless hot water heaters...one for the master bath, and one for the rest of the house.

Given power outages, we put in a generator large enough to run the geothermal system.


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RE: Planning for a new green home

If there is a way to get the deck to the SE corner, do it. We put a partially covered deck there and it is great. It is protected from the prevailing NW winds in the winter and it captures the sun from the south and east in the a.m. when it's cooler in the summer and protects you from the harsh summer sun from the west during the hottest part of the afternoon. We added a ceiling fan which makes it even more usable much of the year.


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RE: Planning for a new green home

Not sure, but I think I used these guys to visualize the overhang and the sun shade on our house....the trick is really late summer where you aren't ready for the heat gain yet, but on the flip side, you still want it in the spring and you don't want to make the house look crazy with too deep overhangs. Also keep in mind it matters how close the overhang is to the top of the window itself.

Here is a link that might be useful: tools


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RE: Planning for a new green home

We have LP gas in the house but only for the hot water heaters, the gas fireplace and the generator. For back up heat with the geothermal, there is an electric back up heat, but we have that turned off and have never needed it. We use the woodstove on a regular basis as heat supplement, and on sunny days, we gain 4 degrees in passive solar.


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RE: Planning for a new green home

I just heard that they're trying to invent solar paint for houses that would essentially serve the same purpose as solar panels but instead of having to install bulky panels you just paint your house. Interesting idea right? This isn't exactly about your house but I thought you'd be interested in this fun fact:)


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RE: Planning for a new green home

What is your climate like? Flat roofs can create problems in snowy areas...snow builds up on them, water puddles after a rainstorm.

You have to compare the advantages and disadvantages of a living roof, a sloped roof with solar panels, and a sloped roof shaded by deciduous trees on the south side to cool it in the summer.

You are unlikely to be able to completely go without a conventional heating system completely in Canada.

What is the wind like in your area? In some areas wind turbines provides power more cheaply then solar power.


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