How to reduce House heating cost

[Mary Fisher]

Through a number of lighting upgrades (e.g., replacing halogen display
lighting with ceramic metal halide track heads)

Can you tell me more about these, please?

Mary

 

[[email protected]]

I wonder how you know the COP.

Those figures are impressive, I think, but what's a COP?

A Coefficient Of Performance is a ratio of heat power moved to electrical
power used to move it, in the same units. For instance, if a heat pump uses
1368 watts of electrical power to move 14K Btu/h (14K/3.41 = 4100 watts)
of heat, the COP is 4100/1368 = 3. If an oil-fired forced-air furnace moves
50K Btu/h of heat using 500 watts for the blower and pump, we might say
the COP is 50K/3.41/500 = 29. If we move 54 kWh of warm air from sunspace
into a living space with the help of a 2 watt damper motor running 3
minutes per day, the COP is 54kWh/0.1Wh = 540,000.

Nick

 

[Paul M. Eldridge]

Hi Mary,

These are excellent questions. I often use terminology that is
unfamiliar to most people and I'm glad you asked for clarification.

Heating Degree Days (HDD) is an indicator of how much energy is
required for space heating. An average daily outdoor temperature of
18C is considered the point at which no heating is required to
maintain comfortable indoor temperatures; when the average daily
outdoor temperature falls below this point, it is assumed that some
form of heating is necessary (generally true for older, less well
insulated and leaky homes, but not necessarily so for more modern,
well built homes; newer homes lose much less heat and passive solar
and internal heat gains from lighting and appliances can often
maintain comfortable indoor temperatures at considerably lower outdoor
temperatures).

To calculate HDD, you average the high and low temperatures of each
day, then subtract the result from 18. So, for example, if the daily
high is 14C and the low is 6C, the average temperature for that
24-hour period is 10C. Subtracting 10 from 18, leaves 8. Thus, the
HDD value for this particular day is said to be 8. When you add up
all the *positive* numbers for the entire heating season, you have the
total number of Heating Degree Days.

With this number, oil, natural gas and electric power utilities can
estimate how much energy residential and commercial customers will
require for space heating. It also provides us with a convenient way
to compare how the winters in one city stack up to another. So, I can
tell that Ottawa's winters at 4,600 HDD are, on average, 12 per cent
colder than those here in Halifax.

COP is another term that isn't well known outside of the heating
industry. COP is shorthand for "coefficient of performance" and it is
used to measure the heating performance of heat pumps. Basically, COP
is the ratio of the amount of heat delivered by a heat pump and the
amount of electricity consumed by the heat pump in this delivery.
Higher numbers indicate better performance.

COP is largely determined by two factors: a) the relative efficiency
of the heating equipment and b) the outdoor operating temperature (the
performance of air-source heat pumps drops off rather rapidly as
outdoor temperatures fall below 0C)

So, for example, the average daily temperature here in Halifax this
past October was 10.9C. For this month, I calculated my heat pump's
COP to be 3.2. That means that for every kWh of electricity it
consumed, it provided me with 3.2 kWhs of heat in return (not too
shabby). In February of this year, the average daily temperature was
-4.8C. At these colder temperatures, my heat pump had to work much
harder to extract useful heat and so its COP was only 2.2. Still, the
heat it provided was less than half the cost of electric resistance
heat (COP=1) and, likewise, half the cost of oil. When outdoor
temperatures drop below -10C, most heat pumps are no more efficient
than standard resistance heat, so I turn it off and use the oil boiler
exclusively.

Hope this information is helpful.

Warmest regards,
Paul

 

[Paul M. Eldridge]

Hi Nick,

You might say Quattro Pro and I have bonded. I have a spreadsheet
that logs the hourly outdoor temperature and the hours the heat pump
operates. With the published specs, I can calculate (with reasonable
accuracy), the COP of this heat pump for each hour it operated.

I can mail this file to you if you wish.

Cheers,
Paul

 

[Paul M. Eldridge]

Hi Mary,

Sure. Originally, there were one hundred and twenty 75-watt,
extended-life halogen PAR38 bulbs used in our store for display
lighting. That represented 9,000 watts of lighting load. I replaced
all of these halogen "track heads" with a number of 39-watt and
70-watt ceramic metal halide fixtures from Halo. Watt for watt, they
produce SIX times the amount of light, offer twice the service life
and with many fewer heads, there's a whole lot less visual clutter.

Here's a picture of some of these heads:
http://server3.pictiger.com/img/258777/other/halo-cmh-heads.php

This article explains the technology is more detail:
http://lightingdesignlab.com/ldlnews/ceramic_metal_halide_sd.pdf

Warmest regards,
Paul

 

[Paul M. Eldridge]

Hi Nick,

Of course, not every house is blessed with great solar potential. Our
maritime climate here in Halifax isn't as kind to us as say that of
Saskatoon. And, sadly, my roofline faces east-west and my southern
exposure is largely blocked by a steep rock cliff and a ridgeline of
spruce and fur trees. For me, a $2,100.00 (CDN) heat pump wins hands
down.

Cheers,
Paul

 

[no one that you know]

Nice wireing! No pride whatsoever.......but this is typical I guess?

 

[Paul M. Eldridge]

Can't comment of the code acceptability of the boiler wiring, but I
can tell you the Tekmar was installed by a licensed electrician. Most
of the zone controls, pumps, values, etc. were simply carried over
from the old boiler and that work was all done by my heating company.

In terms of the feed supply to HRV, central vac and alarm system, that
wss of my own hand; I'm now in the process of insulating and dry
walling the utility room so, as you can see, everything is in state of
mess (the wiring of wall wart, by the way, was done by Chubb, not me).

Personally, I would have preferred if all of these players were more
like Niles Crane, but I'm not about to step in and tell
"professionals" how they should do their job.

Cheers,
Paul

 

[Mary Fisher]

A Coefficient Of Performance is a ratio of heat power moved to electrical
power used to move it, in the same units. For instance, if a heat pump
uses
1368 watts of electrical power to move 14K Btu/h (14K/3.41 = 4100 watts)
of heat, the COP is 4100/1368 = 3. If an oil-fired forced-air furnace
moves
50K Btu/h of heat using 500 watts for the blower and pump, we might say
the COP is 50K/3.41/500 = 29. If we move 54 kWh of warm air from sunspace
into a living space with the help of a 2 watt damper motor running 3
minutes per day, the COP is 54kWh/0.1Wh = 540,000.

I'm going to save that and hope that I can work it out ... I'll let you
know.

Thank you.

Mary

 

[Alan Combellack]

Wow!
I hoped I might get one or two sensible answers but I didn't expect
anything like this. Many thanks to everyone, especially Mr Eldridge, who
seems have become heavily involved in enlightening other people besides me.
Thank you, Sir.
Keeping in mind the fact that we don't have a lot of money to spare for
upgrades, which is why I need to do something in the first place, how does
this sound?
1. Greatly improve insulation and air tightness wherever possible.
2. Obtain and install a heat pump which might cost about C $3000 or so.
This could be an outside air sourced machine or, possibly, a ground source.
I have a largish lot and can easily get some trenches dug and pipes buried
for a few hundred dollars. I believe ground sourced heat pumps have a
better COP at lower and higher outside air temperatures for both heating and
cooling.
3. Take advantage of the sun as much as possible. This would need to be
a mostly passive system such as those described by Mr. Pine. Active systems
are good but tend to cost a lot.
4. Forget pellet stoves as they are too pricey and need constant
maintenance.
5. Nobody raved enthusiastically about an outside wood burning water
heater and, in any case, I am getting old and don't want the hassle of
dealing with refuelling it and disposing of ashes etc.
6. At least one decent sized (30,000 to 40,000 Btu per hour) gas fire in
the main downstairs rooms looks like a good idea as a back up and for
cosmetic reasons. In a real emergency with electricity off for several days
(as happened here in January 1998 during the "Great Ice Storm") a gas
powered stove could be used for cooking as well as heating at least part of
the house. We will not rely on this for the main heat source as gas is
little or no cheaper than electricity.
7. The main "heavy lifting" will continue to be my baseboard electrical
heaters but the thermostats will be kept low and the heat pump forced to do
as much as it can. I very much like the idea of getting 3 to 4 kWhr of
heating but only paying for 1 kWhr (which costs me about 11 Cents at
present). I am not aware of any other fuel source which
I could use which would be more economical. Solar heating, with a fairly
large collection area, could probably match this cost but the necessary
installations might be beyond me, both physically and financially. This
needs further research for me to decide. The house is actually fairly
shaded by a large maple tree (good in summer, mostly bad in winter) and I
would be murdered by my family if I suggested knocking it down. The presence
of this tree was a significant part of the reasons we bought this place 30
years ago. I do have a patch of garden a bit removed from the house on
which some solar structure could be built. Against this is the problem of
getting the heat into and around the house which has no air ducts at all and
installing radiators everywhere would be expensive.
8. Get used to lower indoor temperatures in winter and warmer
temperatures in summer and dress accordingly. Also consider good sleeping
bags. This is not much of a problem for my wife and me since we grew up in
UK and actually we already keep the thermostats set to about 60 deg F (15
deg C). Our son, however, mainly grew up in Canada and seems to think room
temperature should be at least 75 deg F. I'll do the ceiling insulation
though as it is cheap and easy to do. This is my number one priority!!
Thank you all for the advice, all of which will be acted on in one way or
another. If I have missed, or misunderstood, anything important please let
me know.
Alan Combellack

 

[SJC]

But heat pumps are expensive, with a very low COP, compared to some solar
systems, and a house can store overnight heat from sunspace warm air in
its thermal mass. Big Fins (TM) or fin-tube pipe near the top of an air
heater inside a sunspace can collect and store higher temp heat in a tank
for a few cloudy days and hot water for showers, with help from
a greywater heat exchanger.

We might store overnight heat in thermal mass under a foil-covered ceiling,
eg a flat helix with 10'x4" PVC pipes full of water, with no water movement
on average days and tank water flowing through the pipes on cloudy days,
with a slow ceiling fan and a room temp thermostat to bring down warm air
as needed.

Nick

You might do lots of things. But until you can prove anything actually
works with many installations and hard data, then it is still in the might stage.

 

[Paul M. Eldridge]

Hi Alan,

You're most welcome. It sounds like you already have a pretty good
sense of what needs to be done. Without question, insulation and
draft proofing should be your first priority. Maximizing passive
solar gain (and controlling unwanted gain during the summer months)
makes good sense too; a little homework on your part could pay off
handsomely.

And since you want -- and, in Ottawa, need -- air conditioning, the
incremental cost of installing a ductless heat pump versus an a/c only
unit is rather small and the payoff in terms of energy savings is
quite real. I hesitate to mention this, but I bought mine from a
wholesale outlet and had a friend who is a qualified HAVC technician
install it for me; if you have similar connections, you might be able
to save yourself several hundreds of dollars (sorry, I don't want to
propose all of us steal bread from other peoples' mouths).

Now, hopefully I don't muddy the waters too much more, but have you
considered electric thermal storage (ETS)? All Ontario households
will be moving to time-of-use (TOU) rates within the next couple of
years and an ETS system could be one of your more economical solutions
(by shifting a large part of your electricity consumption to off-peak
times, you should be able to significantly lower your heating costs).

For more information on Ontario's "smart meter" programme and local
TOU rates, please see:
http://www.hydroottawa.com/conservation/index.cfm?lang=e&template_id=326

and,

http://www.energy.gov.on.ca/index.cfm?fuseaction=electricity.smartmeters

For a good primer on ETS heating systems, please see:

http://www.nspower.ca/customer_serv...electric_thermal_storage/heatingoptions.shtml

and,

http://www.steffes.com/

Even if you don't go with an ETS system, you should still plan on
putting your electric hot water tank on a timer so that it recharges
during these off-peak times and, likewise, run your dishwasher, washer
and dryer and other major appliances when rates are low.

If you live in an area where you may lose power for an extended period
of time, I would recommend a gas cook top/range (cooker), in addition
to that gas fireplace (btw, if you lose power, a car battery and
inverter will allow you to operate the small blower fan on your
fireplace and this will help extract the maximum amount of heat). I
lost power for nearly two weeks after Hurricane Juan and I was only
one of a handful of people in my neighbourhood who could cook a hot
meal without resorting to their outdoor BBQ. With a gas range and gas
fireplaces, I'm not as worried about major power outages as my "all
electric" friends.

Best regards,
Paul

 

[Paul M. Eldridge]

Sorry, Alan, just an afterthought to my previous post.... if an ETS
heating system proves too costly, with enough thermal mass and with
multiple programmable thermostats, you might be able to shift a
reasonable portion of your existing electric baseboard heat to
off-peak times and continue to use the ductless heat pump during the
shoulder-peaks (and, if need be, on-peak periods) to "top up", so to
speak.

Before spending a lot of money on a new heating system, I would mull
this over first.

Cheers,
Paul

 

[[email protected]]

You might do lots of things. But until you can prove anything actually
works with many installations and hard data, then it is still in the =
might stage.

It's been done many times. This is 300-year old physics

Nick

Tired of Iraq? Do something about it. Learn to halve your energy use
while having fun with math and science.

Join PE Drew Gillett and PhD Rich Komp and me for a workshop on Solar House
Heating and Natural Cooling Strategies at the Pennsylvania Renewable Energy
Festival from 9-12 AM on Saturday September 23, 2006 near Allentown. See

http://www.paenergyfest.com/workshop-info.shtml