M&V Solar Water Heating Guideline - Eskom

Measurement and Verification Standard Guideline for Low Pressure Solar Water Heating Systems v1r1
10 A WORKED EXAMPLE FOR DEVELOPMENT OF THE BASE LINE
AND DETERMINATION OF THE ENERGY SAVINGS OF A LPSWH
PROJECT
The example below illustrates the process of quantifying of hot water usage when
determining a Baseline prior installation of a LPSWH system at a typical low-cost household
having four to five occupants. The LPSWH system and its specifications and SABS Reports
findings are shown in Table 3 in Section 5.2.1. above. A photo of a typical LPSWH used for
the example is shown in Figure 15.
Hot Water Consumption and associated energy determination
Table 9 below is populated from the results on the audits done for the particular house. The
audit is based on the field worker form filled by the M&V team. A sample form is shown at
the end of this example.
Table 9: Example for Baseline calculations
The process used in this example is based on the assumption that the hot water used by
this particular household is heated by an “equivalent kettle” of 2 kW and capacity of 1.8
litres. The water heated by the kettle for bathing, washing and cooking is mixed with cold
water in order to meet the volume needed. Also the water usage for tea, coffee or cooking
is ignored since it will be heated at the same rate by electricity after the installation of
LPSWHs.
Hot Water Usage by
Electricity
Litres Actual Energy T C Thot Tcold Efficiency
Litres Used
of heating
l l kWh o
K kWh/kg.K o
C
o
C %
MORNING 14.4 10.8 1.12 80 0.001167 96 16 90
Morning cooking
tea/coffee
Morning bath/sanitation
(average 4 persons X 1.8 l
each)
1.8 0 0.00 80
37
0.001167 96 16 90
7.2 7.2 0.75 80 0.001167 96 16 90
Morning washing (1 X 1.8 l) 1.8 1.8 0.19 80 0.001167 96 16 90
Cooking (just hot water) 1.8 0 0.00 80 0.001167 96 16 90
Others (babies, minor
washings etc.)
1.8 1.8 0.19 80 0.001167 96 16 90
LUNCH 3.6 1.8 0.19 80 0.001167 96 16 90
Lunch dishes washings 1.8 1.8 0.19 80 0.001167 96 16 90