Ahhh, over 50kWh/day space heating in December

[DamonHD]

...and found that though our mean CH/DHW energy usage Aug/Sept/Oct/Dec was about 30kWh/day in mains gas (a little under 1cuft) which is what I've been doing my calculations based on, in December it was actually over 50kWh/day and in the first three months of this year averaged 46kWh/day.  Yeuck!

http://www.earth.org.uk/saving-electricity.html#meter

Even if we covered our entire roof area in 100%-efficient solar thermal collectors we would only have about half our space heating energy requirements covered.

If we covered every sky-facing surface on the entire property in 100%-efficient collectors we might cover space heating if we had some storage for bad days.

So this tells me we'll never be entirely off-grid on our plot (and shipping in fuel doesn't count)!

Anyway, I'm glad I ordered the next round (20cm/8") of loft insulation today (for June install).

Rgds

Damon

[PHinker]

Damon,

   Not trying to be argumentative but that seems quite high.  Are you considering the inefficiency of your heat source?  If you have an older furnace you might be seeing only 70% (or less) efficiency.

   I'm sure additional insulation will help.  Granted, inefficiencies in your furnace do not change how much mains gas you used but I'm not sure you can directly relate that to something like solar gain from thermal collectors or sun facing windows.

Paul

[BigBreaker]

Check out some of the tips on www.builditsolar.com; they have a lot of good suggestions beyond attic insulation.

I would definitely hunt down areas where air is getting in (and out).  Windows, doorways, eaves, electrical outlets, etc...  Some places will rent you a thermal imaging camera to help spot cold places inside and hot places outside.

I remember you are in the UK, so your insolation isn't the best, but RE heating is VERY doable.

[Capt Slog]

quote:  30kWh/day in mains gas (a little under 1cuft)

30,000 sounds rather a lot of watthours for so little gas.  I know that a cubic foot of gas yields around 1000 Btu, but don't know where you go from there.

,

[Ungrounded Lightning Rod]

According to the unix "units" program a killowatt hour is about 3412.1416 BTU.

So if that 1000 BTU per cu ft is right he's only using about 293 watthours/day, off by a factor of 100.

Now 293 watthours/day is about a 12 watt bulb so it's probably off.  And 50 kWh/day is about 2 kW 24/7.  That's a couple small space heaters on full, which is reasonable for a big house.  (And a great example of why resistance heating with electricity is a really bad idea.)

So it's pretty clear that the "1cuft" number is bogus.  Maybe he could look at the bill and report more clearly what it says.  (If I recall correctly mine is in "units" which are related to the BTU capacity of the gas.)

Presuming it is actually 50 kWh/day to heat that house, it still doesn't sound totally undoable.  Noontime insolation is about 1 kW / square yard.  Rule of thumb around here is 5 solar hours/day but let's be pessimistic and assume half that.  That says 40 square yards of panels (if the combined efficiency of the panels, storage system, and heat distribution system is 50%.  Ten yards by four yards, or 360 sq ft of panel for a first cut estimate.  That would be a VERY small house and yard.

[DamonHD]

The boiler is 70--80% efficient according to its specs.

It is not that old (~4 years).

But clearly you are right and there's realistically 10% or more energy savings to be had simply with a boiler swap.

So, I'm now looking seriously at a boiler upgrade, even a small CHP (combined heat and power) unit that might recover some of the waste as grid-tie power.  After all, when the heat is on we're in and probably not sitting in the dark...

Rgds

Damon

[DamonHD]

Yes, I'm working on trying to get the thermal imaging camera.  Possible summer isn't the best time to do hunting for problems, so anything I find might have to be fixed next time around!  B^>

Rgds

Damon

[DamonHD]

Hi,

Yes the units on the meter are nominally cubic feet according to its legend, but let's just call them the opaque name 'cuft' instead!

I've gone back and forth between the actual bills, which give consumption in kWh, and the units on the meter, whatever they happen to be in fractional cubic parsecs or whatever.

I do believe the 10kWh/day figure from August, for example, which would be just hot water, since a deep hot bath for me would be 4kWh alone.

So unless the gas companies are lying to us, I assume the figures are approximately right in kWh, and the unit shown on the meter is arbitrary.

Still, I hope I've made an error of some sort!

Rgds

Damon

[DamonHD]

Roof area is a little under 50sqm/sqyd.

Insolation in mid-winter (when we most need the heat) is ~0.5kWh/msq/day.

So if I really really improved insulation (>2x) and my collectors were near 100% efficient and I used all the roof area and I didn't care about the collectors cooking in the summer, then it might be possible!

Rgds

Damon

[Lumberjack]

100 percent solar space heat is not usually a good system goal... 70 to 80 percent is generally doable and a very worthwhile project as payback is going to be around 10 years...

If you want off grid a pellet stove might be a thought. there are some multifuel models that burn corn,wood and many other types of bio mass. A small unit together with solar should get you over the hump.

[DamonHD]

Hi,

I have no objection in using natural gas to cover the most difficult times of the year, since it's cheap and produces relatively little CO2 per kWh (though does have Russia's hand on the tap).

Wood may not be viable for a number of reasons here, not least 'Smokeless Zone' legal restrictions and our physical space, but I haven't ruled it out.  The idea of supplementing it with the junk mail we still get is quite appealing.  B^>

Rgds

Damon

[DanG]

Since the energy contained in gas can and does vary from blend to blend it's traded in 100000 Btu units; You seem to be mixing units "Therm" with "cubic feet" here and on the web link. Strike cuft and replace with therm and you're back in the game.

Wikipedia definition

    * Therm (EC) ≡ 100,000 BTUIT[1]

        = 105,506,000 joules

        ≈ 29.3072222 kWh

        The therm (EC) is often used by engineers in the US.

    * Therm (US) ≡ 100,000 BTU59°F[2]

        = 105,480,400 joules

        ≈ 29.3001111 kWh.

    * Therm (UK) = 105,505,585.257 348 joules[3]

        ≈ 29.30710701583 kWh

(1) United Kingdom regulations were amended to replace therms with joules with effect from 1999; despite this, natural gas is now usually retailed in kilowatt-hours, although the wholesale UK gas market trades in therms.

[DamonHD]

OK, I've struck "cuft" as my term for gas and reverted to "unit".  Thanks.  "cuft" is now cruft!

But it's not quite your Therm either: it seems very definitely over 30kWh for example.

Whatever it is, I'll double-check my estimate of kWh against the bill's claim (per unit) when we next get one.

Rgds

Damon

[frackers]

At what pressure is the gas when its volume is measured? It could be cuft since 'natural gas' in the UK is pumped at quite a high pressure...

Sounds like you are in the market for a Whispergen - the joys of waste heat reclaim, Stirling engines and grid tie will all become part of your bragging rights...

[dynaman]

I would not recomend trying to rent an IR camera.  Infrared building diagnostics is one of the more challenging aplications for this technology, and requires a camera with very good resolution along with someone with fairly good understanding of the imaging to interpret the data. Also IR imaging without a blower door does not give nearly enough information to make qualitative decisions for any retrofits, as the biggest problem and subsequently the greatest gains to be made have to do with air infiltration. I do not know what is available to you in Europe, but in the states an energy audit with blower door and camera can be had for less than 400.00 You should get a report that clearly shows all problem areas along with suggested remedies and their payback in months or years. Having been involved with energy auditing for several years I firmly believe that for any one wanting to lower their total energy requirements this would be money well spent. Find a profesional, start with your utility companies. they should be able to give you some very good ideas.

[DamonHD]

Hi,

I don't know at what pressure mains gas is, but I think it's not that high to minimise leaks.

In any case, something like the WhisperGen would be good for when we have to burn gas.  Others in the frame are the Baxi Ecogen and the Energetix GenLec.

Rgds

Damon

[DamonHD]

Hi,

Point taken.  It's the person that needs hiring rather than the gadget!

There is a scheme in London, The Green Concierge Service:

http://www.londonclimatechange.co.uk/greenhomes/green-concierge-service/

to do this sort of thing, and not too expensively.

Rgds

Damon

[richhagen]

For comparative purposes, here is a dump of my energy usage in Chicago from my spread sheet.  I heat 2 floors of my building and provide electricity to my apartment (one floor) only, approximately 1200 square feet per floor.  Basic conservation such as compact florescent bulbs are in place, and my unit is well insulated.  The tenants control their own heat usage. It is a raw dump of data and the prices are not current.  I don't have a breakdown of what was used as electricity and what was dumped as a heat source, but suffice it to say, more conservation will be in order.  The panels would never pay their way at current production rates, and that is unlikely to change here. I am fairly certain I am also losing a fair bit of energy keeping my tired old batteries charged as well although that is not currently metered.  I plan to revise my setup once I get back from my upcoming trips to Fiji and Asia and get caught up on apartment maintenance issues that will become a bit backlogged during my times away.  

 Natural Gas Utility Usage:

 234.46    15-Feb-06   

 252.73    16-Mar-06   

 169.27    14-Apr-06   

 101.6    16-May-06   

 53.84    14-Jun-06   

 36.57    14-Jul-06   

 42.67    16-Aug-06   

 36.57    13-Sep-06   

 67.05    12-Oct-06   

 180.67    13-Nov-06   

 215.18    12-Dec-06   

 203.81    12-Jan-06   

 4.368273973    2006 daily ave therms   

 460767285.9    ave daily Joules   

 Electricity Utility Usage:

 417    Feb-06

 482    Mar-06

 398    Apr-06

 366    May-06

 277    Jun-06

 336    Jul-06

 259    Aug-06

 268    Sep-06

 252    Oct-06

 224    Nov-06

 267    Dec-06

 320    Jan-07

 10.59178082    ave daily kwh

 38130410.96    ave daily Joules

 Here is my recent solar power generation:

 CURRENT DATE    28 March 2008   

 CURRENT AMP HOURS OUT    16360   

 DATE SET UP    23 November 2006   

 TOTAL DAYS    492   

 1 Therm =     105480400    Joules

 1 KWH =     3600000    Joules

 Daily Amp Hours    33.25203252   

 Days    492   

 Total Amp Hours    16360   

 Voltage    48   

 Joules    2827008000   

 Therms    26.80126355   

 Cost per additional Therm    0.83541243   

 Value as gas replacement    22.39010871    Dollars

 KWH    785.28   

 Cost per additional KWH 2006    0.098367

 Value as electricity replacement 2006    77.24563776    Dollars

 Cost per additional KWH 2007    0.12197508   

 Value as electricity replacement 2007    95.78459082     Dollars

 Typical Daily Electrical Usage    38130411    Joules

 Typical Daily Natural Gas Usage    460767286    Joules

 Average Daily Production    5745951            Joules

 Percentage of energy usage produced    1.15%   

 If used as electricity, % of electric     15.07%   

 Percentage of Nat. Gas usage produced    1.25%     

Same conclusions though, I would need some combination of more land, more efficient panels, and lots of conservation if I had to generate all of my power on my property.    Even more if one factored in all of the products in use, transportation, food, etc.  Just trying to have a bit of fun with it though, Rich

[richhagen]

I've often joked that I could heat my home with the junk mail delivered and circulars tossed on my front steps.  It would cost me a bundle in additional insurance for wood heat here though.  Rich

[Capt Slog]

It was late last night when I first posted this, and I wasn;t about to get a calculator to start checking, but I too made it a factor of at least 100 out.

I think the cubic foot measure on your bill is in HUNDREDS, and I'm prtty sure that is what it says on my meter after the numbers.

It certainly didn't seem correct that 1 cubic foot of gas could provide the same amount of heat as a 1kW bar left on for 30 hours.

Whatever, I'm pleased to see that you are making it work, and "more power to your elbow"  :-).

.

[BigBreaker]

It will be hard to understand your heating needs until your building envelope is tight and your insulation topped off.

I have often been shocked by the draftiness of buildings in the UK, though perhaps that is owing to the desire to retain original features and lack of new residential construction.  Those 1950s windows are just horrible!  Stone construction has a nice thermal mass but terrible thermal conduction... etc...  you just don't see too many 2x6 framed, super insulated, vapor barrier, insulated slab, triple pane casement window types of house.

[DamonHD]

Not that drafty in this house, thankfully.  All double glazed, etc.

Rgds

Damon

[DamonHD]

Hi,

"More to my elbow and less to my combi" could almost become a family motto.

Maybe to accompany a coat of arms with solar panels (thermal and PV) rampant against a verdant field of biomass?  B^>

Rgds

Damon

[dynaman]

That looks like something worth checking into. It is important to remember that the only thing in your direct control is how much energy you require. Get that piece under control and you have many more options as to the energy source you could utilize. Keep up the good work and keep us informed of your progress.

[DamonHD]

Further examination of the meter suggests that one 'unit' is indeed 100cuft, which would make much more sense, and revealed a (smaller) digit in the tens column that I had not noticed before and that might make usage tracking a little less clumsy!

Thanks for all the input...

Rgds

Damon

[Gregn]

50kWh a day sounded high to me also, so I checked our Gas bill and did some conversions/calculations:

This last Nov. we used 5Mcf of natural gas, (that's 5000 cu/ft of gas).

Energy conversion (found on the web) says 1 Mcf gas = approx. 300 kWh, so...

The energy used for heating the house, stoves, and water heater was equivalent to 1505 kWh = 1505/31 days = approximately 48.55 kWh/day of gas mainly for space heating.  Wow!  I was amazed how close this number was to the original poster's numbers.

Obviously there's a lot of variables that we are not talking about but, yea, I could definitely believe 50kWh a day for heat.

When I look at the energy comparison of our electric bill vs. our gas bill, (almost the same, about $59), it really makes me appreciate how much more energy you get per Watt (or more importantly, per $) of natural gas vs. electricity.


Greg

[DamonHD]

But electricity is a much higher grade of energy than heat from burning gas: indeed the ratio in prices between 1kWh of gas and electricity in the UK is about the expected CoP of a decent heat-pump, thus making them more or less equivalent in terms of useful work.

Anyway, I'm happy to say that this year, numbers just in, I don't think that we can have gone over 40kWh/d on space heating and the highest daily consumption including DHW and cooking in the coldest week of this very cold December was 39kWh/d.  (Heat demand in terms of HDD12C has been up about 30% this year and our gas consumption down 7%!)

Rgds

Damon

[Gregn]

Hi Damon,

In my hast to post I guess I forgot to show the price/energy comparison...

Our energy prices between gas and electric for Nov. was $56 for electric, & $61 for gas.  We used approximately 380 kWh of electricity vs. the energy equivalent of 1505 kWh of gas.

That's around 3.5 times as much gas as electric, for about 5$ more!

But like you said, (I think), you can't watch a gas TV or surf the web on a gas computer.


Best Regards and Happy New Year.

Greg

[taylorp035]

50 kwh a day would be nice for my house      I had a few bills that averaged 200 kwh a day... kinda scary to think it was 10 kw 24/7.  Then there are the months the electric company estimates your bill.  They once estimated it at over 8000 kwh.  Now seriously, how do you use that much power in a normal household. 

I don't like the idea of gas.  Too unreliable in the winter and the prices aren't very steady.

[WindriderNM]

how about gas lights probably very efficient if you also consider the amount of heat you get from them.l

[DamonHD]

Let's not get off on this old canard about using general lighting as heat (very little of the energy becomes light, the heat generated is near the ceiling, no good in summer, etc, etc).

Rgds

Damon

[DamonHD]

Borrowed a thermal camera last night.  Images start here:

http://gallery.hd.org/_c/natural-science/_more2011/_more02/thermal-imaging-of-house-interior-and-exterior-and-nearby-on-chilly-February-evening-about-6C-ambient-with-Flir-Systems-b40-in-Kingston-London-England-1-DHD.jpg.html

I've not yet done any annotation on these...  But I didn't find any real horrors.

Rgds

Damon