Making Homes More Energy Efficient

Interesting and useful, on my glass sliding doors upstairs and down, the heating outlet is right above the glass door blowing down on it. I just have vertical blinds on the doors. If I close the blinds, I'd guess I block the vent blowing on the window but typical for a winter day, the blinds are open enough that I'm sure they get air movement.

I wonder if I put a directional cover on the vent so it blows away from the glass doors if that would help?

 

Are these opposing processes, then ?

Is a "too" tight fitting blind prone to glass cooling that will lead to condensation ?

 

I believe it will still get condensation, but without circulation the total amount of water available to condense will be very small. A loose fit will allow the entire room's air to cycle through, vastly increasing the available water to be condensed.

 

Isn't 4% of $1000 $40 bucks?

 

So people that could afford to do the audits took advantage of rebates that could have been better served to the not so well to do? Strange viewpoint of a congregation. I would have thought the congregation would have tried to help less fortunate people that would definitely benefit from having some relief from lowering their bills.

 

Corwyn was talking about the monthly payment to pay off the loan in 30 years.

 

How many watts are your panels? What kind of inverter, or micro inverter was used? I know you are way up in the northern part of the country, but your yield seems a bit low with my guestimation of having at least a 200W panel. Please follow me here:
200W (estimation) x 29=5800W or 5.8 KW.
5.8KW x 5 sun hours a day= 29kWh/day
29 kWh x 30 days/month= 870 kWh/mo
870 kWh x 5 months= 4350

I suppose the winter sun being lower in the sky and less sun hours throughout winter may be the culprit in my calculations. I have never been to Maine. But I am also guessing my 200W choice is smaller than what was used. We install 240-245W panels in sunny Colorado at my company. You don't have some type of shading issue do you? Glad to hear you went solar. Now you also will have little ill effect of rising electric bills. If you don't mind, how did you go about financing your system? Loan through a local bank? This is what I ask clients to try because leasing is typically in favor of the leasing company, not the client. I won't even offer a lease here. I would feel like I was ripping off the client. But maybe in other parts of the country it may make sense to lease???

 

Aahh, that makes sense! Thanks for clearing that up. Corwyn sounded too versed to make a mistake. I thought maybe he had a fat finger on the "0" key. My mistake!

 

This sounds about right for a sky without a cloud in sight year round, if the panel rotates to face the sun head on. Here is the paper napkin calc (the only kind I know):

Average annual sunlight is 11.5 hours a day
The incident sunlight on the panel is a sine function, so about 63.7% of perpendicular sun throughout the day is actually collected
20% of collected energy is lost in transfer to AC etc.
Multiplying it all up, 11.5*63.7*0.8 = 5.86 "sun-hours."

If you are not familiar with PVWATTS, you are in for a treat
If I remember right, my high altitude, New Mexican climate averages about (what you are calling) 6 sun-hours a day.

 

We have had a few clients that have done windmills. We didnt install them. The owners overall didnt get the power they thought they would from the turbines. My opinion is that unless you go big, like Vestas big, it isn't worth the money vs going with PV solar. We get decent wind off the mountains out here, but wind isnt constant. So the power from wind turbines is unpredictable. And the cost of large poles and setting those poles is $$$. I do like the idea of http://maglev.net but on a smaller scale. Mostly the reason for that is there are no poles so service is easier. Also the wear on a system like that is different than a typical turbine.
If you go solar you have no moving parts in a panel, 25 year warranty on the panels and micro inverters that we use. So even if something breaks, we know exactly where to go to fix the problem because there is also lifetime monitoring that shows production panel by panel. And we can design a system size pretty accurately based on about 25 years of solar data. Unless you have a shading issue that wouldn't allow solar to be installed, I would look in that direction. But that's just my opinion.

 

I am familiar with PV Watts. It is quite conservative. We use it all the time because our utility company requires it for system sizing to make sure we stay within our state 120% rule set by the Colorado PUC. And you are correct in the NM being about 6 hrs average over the course of the year. We are also in that ballpark. Your mention of no cloud in sight is probably a factor in Maine more than our part of the country. But you also have an average amount of sun hours per day that is used to base a system over the course of the year. Most of our installs are in southern Colorado. And this is real world, not PV watts. If you run the numbers with that average for our area, you will see the math in real world vs PV watts are different.

I am guessing the yield mentioned above is low right now because it was installed about a month, give or take, prior to winter solstice, where the sun is 30 degrees lower than summer solstice. Hence many fewer hours to make power than my mentioned 5 hrs. After jumping on PV Watts V1 and going to Maine, punching in 5.8KW as a system size guess and raising the efficiency to about 90% (we use micro-inverters that have a higher yield and less loss than typical string inverters overall) and add the last 5 months I get a bit higher yield than what I mentioned above. But I just used the latitude vs the roof that the system was installed on. I guess there are also the variables like we havent been through 5 total months since Nov and we don't know when in Nov the install was done. More than anything I wanted to converse over a solar system because this is what I do for a living.:rockon: Sometimes I need to quit reading the technical stuff on PC and take a breather. There are tons of smart people on this forum! It makes my head hurt...

Have a great night. I'm off to bed. Doing an Outback inverter off grid training all day tomorrow.

 

JustJeff,

I didn't realize you are a PV installer. That's great
Perhaps you know the answer to a question I have wondered about regarding PVWATTS. Does it take altitude and ambient temps into account ?

 

That heating outlet was put there for a reason. Some possible reasons are: 1) The glass would have condensation otherwise, the warm air keeps that from happening. 2) The heating contractor was afraid of 1), even though it isn't an issue, and it is a CYA tactic. 3) The glass is a large cold radiating surface, which makes people near it feel cold, even though the air temperature is warm enough. Warming might actually be more efficient (of the two choices the HVAC guy had). 4) HVAC guy was CYA about 3).

You can try temporarily sealing the outlet and seeing what you get. In the long run large expanses of glass should be insulated (interior storms can be made for large doors, but it takes a different style than for windows, contact me off-list).

 

You misunderstand the project. Note the "no tax savings" part of the original description. This wasn't a project to help the poor. We have plenty of those. This was an offer open to anyone in the congregation, serving a specific purpose within the congregation. It was the last in a long series of projects to see what, if anything, we could do to motivate the congregation to reduce fossil fuel use.

Answer: Not much. We have now officially given up on trying to do that.

It went hand-in-hand with an audit of the church campus, which itself uses about as much energy as 12 average houses. The question was, if we have $1 to spend on conservation, does our little church-related group get better return investing directly in the campus, or indirectly in the congregation? Precisely because this was not aimed at the poor, no tax deduction could be taken for the donation covering the subsidy.

As noted in the description, most of those who got an audit, after seeing what an audit was, would not have been willing to pay full price for it. So the subsidy was required to get participation. But in response to the comment here, that the auditors must have been incompetent to have gotten so little average savings, I speculated that, at the low price, we may have differentially attracted individuals who didn't have a lot of low-hanging fruit for energy savings. State of Maryland says 20% is the average (projected?) savings identified in energy audits there. I calculated an average 11% for these audits based on the auditors guesses of likely energy savings. That's the projected savings if everyone complied with all the auditor's suggestions. Which becomes more like 6% based on actual compliance to date.

One of the takeaways I got from interviewing energy audit firms is that there's just plain a lot of bull**** thrown around about potential energy savings. And not a lot of hard-numbers analysis of actual impact. Hence this little project, where we at least bothered to try to monitor the real-world compliance rate.

Edit: And I guess for any of this to make sense, you'd have to realize that respect for the environment is a core principle of Unitarian Universalist churches. Literally part of the creed. Hence the time and effort spent on this project.

 

PVWatts v1 is based on Standard Test Conditions <STC>. So 1000 Meters squared at 25 degrees celcius. This is possibly why we in the sunny states see more yield at higher altitudes and bright sunny cold winter days than pvwatts calculates. I never really thought too much about that. So thanks for asking the question. I just had an aha moment.

 

Been on the road, and missed a bunch, but wanted to add, most small scale (home scale) wind is a looser. Most people over estimate their wind potential, by a lot! Additionally, small scale hardware is subject to. Huge live loads in tough environments, and is generally short lived. Compared to the WH net cost of PV solar compared to small scale wind, PV winds hands down in nearly every case that I know of!

Icarus

 

Couldn't have said it better myself. PV RULES! :cheer2:That's why we don't offer wind turbines at all.

 

I installed a Skystream wind turbine in 2006. I was one of the beta testers for the unit. It's a nice design and has been reliable. I am a bad site for wind - too many trees and in a modest wind climate. If you are installing a turbine you need location, location, location. Location #1) Be in a high wind zone area, #2) have a open area with at least a 300' clear radius around the unit - preferably on a hill, #3) as tall a tower as possible. Wind Turbine

 

This too is essentially correct, but I would add one ironic twist,,,

Generally, if you have enough wind for small scale wind to be productive, you probably have too much for long lived hardware. While height mitigates some of the potential gust damage/turbulent air issues, once you get more than ~15 mph AVERERAGE (~12 is considered the minimum average to be useful) the hardware takes a beating.

At the per watt price of PV, with raw panel prices under ~$1/watt, 500 wats of PV might put out an average of maybe 1-2kwh/day on averge, at a cost of $500 for the PV. What small wind will, for a cost of $500 produce 1-2 kwh/day,, essentially for ever? (hint,, NONE!)
(example only, scale up or down as you see fit!)

Icarus

 

Well said on the wind turine taking a beating. And most poles aren't made to fold down for easy service.

As for the solar PV, less than a buck a watt is stretching it, unless you buy a container at a time. Plus you failed to add the price of inverters and wiring. But yes, hands down PV is a better way to go for reliability and yield over the term of system life.