2014 Green Conservation Plan

[pdf27]

Done so far since 2010 when we bought the house (~1,000 sq ft mid-terrace):

1. New condensing natural gas boiler fitted to replace 1970s one (~90% efficient versus ~60%), separate upstairs and downstairs zones.
2. Underfloor insulation fitted downstairs.
3. Draught lobby fitted by back door.
4. New kitchen with A++ rated fridge/freezer and A+ rated oven.
5. New hot water cylinder.
6. LED or CFL lights everywhere.
7. 5kW (1700 BTU/hr) wood stove fitted, capable of heating the whole house down to about -5 deg C.
8. Water saving plumbing in the bathroom.
9. Dishwasher plumbed in to hot water supply so it uses water heated by gas not electricity.
10. Reasonably high-efficiency washing machine.
11. Couple of solid walls insulated internally.
12. Growing some of our own food.

Still to do (this year, maybe - first baby due in June!):

1. Solar PV - 4kW system facing ESE.
2. Solar Hot Water.
3. New windows - currently 25 year old UPVC double glazing, bit draughty and has condensation in places.
4. Expand vegetable garden to ~3x current size. That was to be this winter but I broke my collarbone falling off my bike and it's only just been fixed (back to work for the first time this morning).

Current usage for the past rolling year is ~2,500 kWh of electricity and ~9,000 kWh of gas. Once all the improvements are done anticipated values are roughly net-zero on electricity and ~5,000 kWh of gas, plus a few cubic metres of wood per year.

 

[woodgeek]

Still to do (this year, maybe - first baby due in June!):

1. Solar PV - 4kW system facing ESE.
2. Solar Hot Water.

Current usage for the past rolling year is ~2,500 kWh of electricity and ~9,000 kWh of gas. Once all the improvements are done anticipated values are roughly net-zero on electricity and ~5,000 kWh of gas, plus a few cubic metres of wood per year.

5kW = 17000 BTU/h.

I assume you have read the bit that suggests adding more PV + a HP water tank. IIRC, you worry about the grid battery. Like to hear your logic.

 

[Ashful]

Still to do (this year, maybe - first baby due in June!):

Congratulations. Your available time for further improvements is about to get cut by about 80%. When kid #2 comes, expect that to get cut in half again, to 10% of pre-kid levels.

 

[pdf27]

Congratulations. Your available time for further improvements is about to get cut by about 80%. When kid #2 comes, expect that to get cut in half again, to 10% of pre-kid levels.

Which is why all the stuff I need to do apart from the gardening is already done - everything else I've got to pay someone to do (and the money is going too, but none of it is urgent!).

 

[pdf27]

I assume you have read the bit that suggests adding more PV + a HP water tank. IIRC, you worry about the grid battery. Like to hear your logic.

UK law is the obstacle there - we don't have net metering due to a wrinkle of the tax system. That means you can displace your own normal consumption (saving 16p/kWh in my case), export it at 4.4p/kWh or use it to heat hot water saving the 3.5p/kWh I currently pay for natural gas. Currently they assume you export 50% of your consumption no matter what, but net meters are coming in by 2015 and so exporting to the grid will be better than replacing natural gas.

As far as HP Water Heaters go, they don't make sense if you ever run them on grid electricity and have gas anyway in the UK. Even with a COP of 3 they cost about 5p/kWh of useful heat, when I can heat the water with gas at 4p/kWh. There's a bit of a saving if you're using PV, but if I can fit solar thermal at about the same cost as a HPWH (and keep the gas boiler as a winter backup more easily) that works out better.

This doesn't apply to the US case - your electricity prices are lower, and most of you don't have natural gas so heat with much more expensive oil. Most of all, you have net metering so can use the grid as a giant battery so far as finance is concerned. I can't over here.

 

[velvetfoot]

pdf27,
I saw that your collectors are facing ESE. That is approx. where my roof is facing, but I was under the assumption that S is ideal. True? Thanks. VF

 

[pdf27]

pdf27,
I saw that your collectors are facing ESE. That is approx. where my roof is facing, but I was under the assumption that S is ideal. True? Thanks. VF

South is ideal, losing a bit as you go further East or West. They aren't installed yet, but the calculation suggests that it should provide about 70-80% of the generation of a straight south setup.
Minor correction - It's actually WSW, I was having a brain fart. It's a mid-terrace house with roofs facing WSW and ENE, so I don't have much choice. I'm also a long way north - roughly level with southern Alaska or Newfoundland. The main effect (apart from reduced total generation) is that in summer the sun is above the horizon for a very, very long time so it'll keep generating until relatively late in the evening. If you want to look at it, SMA Sunny Design is pretty good for a free almost professional tool, and PVWatts is pretty good for a quick look. Both of those let you put in location and roof angle, which should let you compare your orientation to due south.

One thing to remember - we both work during the day, and probably will continue to do so after the baby arrives. That means the majority of our electricity consumption is when we're at home in the evening - and since we don't have net metering that actually makes a WSW orientation quite good since it matches generation and consumption to each other relatively well. If you have net metering (as most US states do) then this advantage doesn't apply.

 

[velvetfoot]

Thanks. We have trees too, (that we don't want to cut down!)

 

[pdf27]

Thanks. We have trees too, (that we don't want to cut down!)

That's a potentially big problem - PV panels really, really don't like partial shade. If the bit of the roof you want the panels on is shaded for part of the day, assume you'll get very little generation during that time.

 

[velvetfoot]

Well, the actual story is that a solar company came out and gave us an estimate on pylon mounted collectors in the backyard, which my wife didn't like. I didn't like the collectors mounted on our metal roof, so, never got an analysis on that. I might change my mind-the tree situation might not be as bad as I think.
Thanks again.

 

[begreen]

That's a potentially big problem - PV panels really, really don't like partial shade. If the bit of the roof you want the panels on is shaded for part of the day, assume you'll get very little generation during that time.

That can be mitigated by using inverters like the Enphase on each panel instead of serially connecting the entire array.

 

[jebatty]

The LED strip under cabinet lighting is installed and my wife loves it. Maximum power is 20 watts vs 65 watts for the replaced halogen puck lights. The LED strip also can be dimmed down, and I suspect once we find the "turn it on and leave it alone" setting, power usage will be around 12-15 watts.

Just got back from a 10 day trip, and the electric meter showed 5kwh/day of background usage, not including dhw and supplemental electric heat. That's a little higher than I expected, so time to track down the users: freezer, refrig, and DSL phone are the expected major users, but then there is the background use by the control circuits of the electric stove, microwave, and other things I will have to ID that still are always on. Our normal general use when we are home has dropped to right around 10kwh/day, down from close to 20kwh/day prior to our renewed passion to find and eliminate wasted electric use. Since we just made the conversion to nearly all LED lights, I will be interested to see how much the 10kwh/day average use drops.

 

[Highbeam]

Just got back from a 10 day trip, and the electric meter showed 5kwh/day of background usage, not including dhw and supplemental electric heat. That's a little higher than I expected, so time to track down the users: freezer, refrig, and DSL phone are the expected major users, but then there is the background use by the control circuits of the electric stove, microwave, and other things I will have to ID that still are always on. Our normal general use when we are home has dropped to right around 10kwh/day, down from close to 20kwh/day prior to our renewed passion to find and eliminate wasted electric use. Since we just made the conversion to nearly all LED lights, I will be interested to see how much the 10kwh/day average use drops.

This is why energy monitors are so great. I will be curious to see how low you can go.

 

[WiscWoody]

We've got so many blankets on our bed right now I feel I'm suffocating.
It may be time to install the heated mattress pad on the bed.

All the beds in my home have heated mattress pads. The King size on uses 110 watts over side but I rarely have it hotter than the 2 setting, cycling on and off. It works well having a wood stove for heat as the bedrooms are cool. I sleep better in a cool room anyways.

 

[WiscWoody]

My home is well insulated and blower door tested tight. Since I can't have a drain field septic system I have a 3000 gallon holding tank and water conservation has been a goal since moving into the house full time instead of just the weekends before. I just installed the second dual flush commode to replace a 1.6 gallon flusher. The toilets don't get flushed on every use but it's just myself grossing out. Lol

I use 260-320 KWh of power a month so that's under control IMO.

 

[jebatty]

We have a gravity drainfield, but our goal too has been to reduce water usage. One toilet gets used most of the time, and dual flush is on that one (if it's yellow let it mellow, if it's brown flush it down); other toilet is the 1.6 gallon variety. We never let the faucets run, and we have to remind guests to not let the faucets run.

Since the solar install our goal is less than 300 kwh/mo general use plus 100 kwh/mo for the electric hot water heater, or about 13 kwh/day average. Since Oct 28 when the solar went active, our average daily use for these is a little over 12 kwh/day, and usage should be dropping as in Jan we converted to nearly all LED lighting.

We have supplemental electric heat to keep the basement at 50F and to heat the house when we are gone for more than a day. This winter that has been a killer: 2810 kwh for heat and electric hot water Oct 28 - Feb 4 (about 735 kwh ave/mo for heat +100 kwh ave/mo for hot water ). Our goal is for the solar over the year to meet 100% of our electric usage, including heat. Time will tell. I'm looking for an inexpensive way to get additional heat into the basement. Our wood stove does not have the capacity to do this and also keep the main level of the house comfortable.

On the other hand this heating electric translates to about 14 lbs/wood/day if wood heat was used for that heat, and about 2 lbs/wood/day if wood heat was used for hot water, or about 1-1/2 cords of aspen stove wood over a season.

 

[Ashful]

Not criticizing, but just curious... in the case of a properly functioning septic system, why such interest in reducing water usage? Sure, a few pennies are spent on pumping it to the surface, and a some portion is lost to evaporation when put into your drain field, but it seems like a mostly closed-loop system to me. It comes out of my yard, and goes back into my yard. You haven't discussed reducing the waste it carries (don't stop pooping!), just the amount of water that waste is conveyed by or into which it may be dissolved.

 

[jebatty]

From what I have read, excess water is not good for septic systems with drain fields. It's pretty hard to get too little water in a septic tank but easy to get too much. Excess water can push solids into the drain field which ultimately will clog it. Also, excess water can slow down the decomposition of the waste in the septic tank and not allow it to decompose as much as it should before entering the drain field.

Edit: Also, IMO wasting any resource rarely if every is a benefit. Potable water is a precious resource.

 

[Highbeam]

From what I have read, excess water is not good for septic systems with drain fields. It's pretty hard to get too little water in a septic tank but easy to get too much. Excess water can push solids into the drain field which ultimately will clog it. Also, excess water can slow down the decomposition of the waste in the septic tank and not allow it to decompose as much as it should before entering the drain field.

Edit: Also, IMO wasting any resource rarely if every is a benefit. Potable water is a precious resource.

It's not so much a green-conservation thing but it is good for your drainfield to underutilize it. Gravity drainfields are progressive failure systems and minimizing flows will maximize life. They are doomed to clog eventually from the non-degradable lints, and hairs that will make it out and form a matt on the interface between soil and gravel.

 

[Where2]

That can be mitigated by using inverters like the Enphase on each panel instead of serially connecting the entire array.

I've got a large royal palm tree in the neighbor's yard that partially shades my PV system in the early morning (until 11AM today), and a large oak tree in the other neighbor's yard that partially shades my PV system in the late afternoon. My enphase inverters handle the minor shading issues very well. My system faces ~16° west of due south, yet I'm still averaging 119% of estimated output over the last 6 months.

Toward my 2014 goals, I continue to look at HP water heaters and am searching for a residential ground mount system that can withstand a 3-second gust of 160mph while holding 16-20 panels.

 

[jebatty]

The 2014 Plan now also includes a 2.5' x 24' downspout hot air solar collector, facing SW under some windows, to supply hot air into our basement supplanting some of the electric heat we need to keep the basement at about 50F. I'm going to try to get it built and installed by March/April so we get some use out of it yet this winter season.

 

[maple1]

Keep your camera close - interested in seeing that one.