Household Utilities: Power Requirements:
Residential House Energy Requirements.
The
simplest and most accurate method to estimate residential energy requirements
is to first look at historical data. Reading the electricity meter weekly
gives the current usage pattern. Reviewing past electricity bills provides
seasonal trends. My power supplier gave me the my quarterly power usage
for the past few years over the phone.
The following is the historical electricity usage by the Newton's,
whilst two adults lived in a typical brick veneer house in Brisbane,
with electrical cooking, heating, cooling and hot water services. Note
that the winter months have higher power consumption in both tariff
11 and 33. The summer months have lower power demand.
Tariff 11 :- lights, TV, stereo, oven, stove, vacuum cleaner, washing
machine, computer, printer, fridge, and other small electrical appliances.
Tariff 33 :- hot water system
Historical power
usage
|
Dates
|
kWh/day
Tariff 11
|
kWh/day
Tariff 33
|
Total kWh/day
|
|
12/97-3/98
(Summer)
|
7.0
|
5.6
|
12.6
|
|
3/98 - 6/98
(Autumn)
|
8.4
|
6.7
|
15.1
|
|
6/98 - 9/98 (Winter)
|
14.3
|
7.1
|
21.4
|
|
10/98 - 12/98 (Spring)
|
7.4
|
3.0
|
10.4
|
|
12/98 - 3/99
(Summer)
|
7.3
|
3.9
|
11.2
|
|
3/99 - 7/99
(Autumn)
|
11.2
|
8.3
|
19.5
|
|
7/99 - 9/99
(Winter)
|
9.6
|
9.8
|
19.4
|
|
9/99 - 12/99
(Spring)
|
6.9
|
8.9
|
15.8
|
|
12/99 - 3/00
(Summer)
|
7.3
|
8.4
|
15.4
|
|
AVERAGE
|
8.8 |
6.8 |
15.7kW hr/day |
Tariff 11 increased in winter because of the use of electric heating
and increase use of the oven for cooking. It is a concern that homes
with air conditioning are now using more power in summer then winter
(and that is not because they have reduced their winter consumption)
Tariff 33 was higher lower in summer months as I would turn the thermostat
on the HWS down during this time. The exception being Spring - Summer
99-00 when the thermostat was not adjusted.
Australian Green house Office, 1999, shows the following breakdown
of residential
Electricity use in Australia.
|
Electricity usage
|
Percentage
|
|
Space cooling
|
1
|
|
Cooking
|
4
|
|
Water Heating
|
27
|
|
Electrical Appliances
and equipment
|
30
|
|
Space heating
|
38
|
The
Newton House:
|
Electricity usage
|
Power Saving %
|
|
Space cooling
through insulation,
cross ventilation, and shading
|
1
|
|
Cooking -
Gas
|
4
|
|
Solar Water Heating
with gas booster
|
27
|
|
Electrical Appliances
and equipment
No standby power, wise purchase
|
5
|
|
Space heating
through insulation,
thermal mass, winter sun gain
|
38
|
|
Power Reduction
|
75%
|
Power
Planning
On Paper we can reduce our power consumption in our household by 75%
without compromising our lifestyle. Given this we have designed
a solar power system that will provide a constant 5kw per day. That
is ~ 1/3 of our historic power consumption.
As the source of this power is a a stand alone solar power system, we
will reduce our greenhouse emissions by 100%.
Stand alone
power is not a cheap option, but keep in mind that anyone can purchase
green power through their power supplier. This power is sourced from
green power sources such as wind, landfill and biomass.
Consider
the cost of the Newton's power consumption in their historic home and
their sustainable powered home if solar power was not an option. Green
power can be purchased from the local energy authority at $0.17/kW,
coal power can be purchased at $0.14/kW:-
|
Coal powered house
|
15.7kW/day @ $0.14 kW
|
$717 pa
|
|
Green powered house
|
15.7kW/day @ $0.17kW
|
$870 pa *
|
|
Sustainable designed green power house
|
5 kW/day @ $0.17kW
|
$277 pa *
|
* reduced greenhouse emissions by 9.2 tonne per year
The following
calculations show the estimated energy requirements for the Newton House
on completion.
|
Electrical appliances
and Equipment
|
Wattage
|
Max Daily Hours
|
Watt hours
|
|
Kitchen: Refrigerator
|
240
|
10
|
2400
|
|
Microwave
|
1200
|
0.1
|
120
|
|
Laundry: Washing Machine
|
1000
|
0.3
|
300
|
|
Iron
|
1200
|
0.3
|
360
|
|
Lounge: Television
|
100
|
3
|
300
|
|
Stereo
|
50
|
5
|
250
|
|
Study: Computer
|
100
|
3
|
300
|
|
Monitor
|
165
|
3
|
495
|
|
Printer
|
120
|
0.1
|
12
|
|
Lighting: Bedroom
and WIR
|
18
|
0.5
|
9
|
|
Bathroom
|
15
|
1
|
15
|
|
Toilet
|
40
|
0.25
|
10
|
|
Laundry
|
40
|
0.1
|
4
|
|
Courtyard
|
27
|
1
|
27
|
|
Study
|
32
|
4
|
128
|
|
Kitchen
|
32
|
3
|
92
|
|
Little Deck
|
18
|
0.5
|
9
|
|
Pantry
|
11
|
0.1
|
1
|
|
Lounge
|
32
|
3
|
96
|
|
Back Deck
|
18
|
0.5
|
9
|
|
TOTAL watt hours
|
|
|
4937
|
