The De Zalze Residential Estate implemented a 5-year electricity plan with objectives of reducing costs, improving efficiency, and reducing environmental impact. Initiatives included awareness programs, smart meters, time-of-use rates, and guidelines for solar generation. Evaluation shows the estate's electricity costs decreased relative to other areas and peak consumption reduced, showing positive trends but requiring more participation.

1. De Zalze Residential Estate Electricity Plan Implementation
(February 2015)
Abstract-During 2009/2010, the De Zalze Estate's HOA Board of The measurement of electricity performance included
Author - C A Visagie (Gateway Utility Solutions)
Directors approved a 5 year plan for electricity with the following
objectives:
Reduction of electricity cost
Improved energy efficiency
Reduced impact on the environment
The initiatives that were introduced included energy efficiency
awareness, smart metering, time-of-use tariffs, timers and
guidelines for individual own generation such as solar. The De
Zalze Estate buys its electricity directly from Eskom at the Miniflex
tariff and Estate's policy dictates the recovery of actual electricity
costs from the residents.
The measurement of electricity performance included the total
consumption trend, purchase price from Eskom, average price
paid by the De Zalze's residents compared to nearby
municipalities and the percentage power used during peak hours.
These indicators all show positive trends and confirmed that the
De Zalze is on the right track, but still require wider participation
of all the consumers on the Estate.
Index Terms- Keywords used include energy efficiency,
electricity tariffs, peak consumption and time differentiated
tariffs, Critical Peak Day (CPD) tariffs.
1 INTRODUCTION
During 20 10, the De Zalze's HOA Board of Directors
approved a 5 year plan for electricity with the following
objectives:
Reduction of electricity cost
Improved energy efficiency
Reduced impact on the environment
Energy initiatives can generally not be implemented
overnight and it takes some time for new ideas to gain
acceptance. However, it is now nearly 5 years later and
this report takes an early view of trends in the main
indicators to establish if the Estate is still on the right
track. Investments have been made with the expectation
of positive outcomes.
The biggest challenge is always to get wide
participation from residents on a large Estate with diverse
interests, especially where electricity cost does not form a
major part of the expense of the average household. There
is however a growing environmental awareness, which
includes concerns over scarce resources such as electricity
and water and more recently, the threat of load shedding.
The initiatives that were introduced included energy
efficiency awareness, smart metering, time-of-use tariffs,
timers and guidelines for individual own generation such
as solar. De Zalze buys its electricity directly from
Eskom at the Miniflex tariff and the Estate's policy
dictates the recovery of actual electricity costs from the
residents.
the total consumption trend, average purchase price from
Eskom, average price paid by the De Zalze's residents
compared to nearby municipalities and the percentage
power used during peak hours, both morning and evening
peaks. These indicators all show positive trends and
confirmed that De Zalze is on the right track. However, it
still requires wider participation from more consumers on
the Estate.
2 ELECTRICITY STRUCTURE
De Zalze buys its electricity directly from Eskom at a
tariff called Miniflex, which is the best available tariff
structure for the Estate taking into account the
consumption profiles of De Zalze. It is predominantly
based on the energy consumed and has 6 time periods
with differentiated pricing. The time periods consist of
Peak, Standard and Off-peak categories for summer and
for winter, with the winter peak pricing at a very high
level.
The major consumer groups on the Estate are:
i. Wine Cellar, restaurant and lodges
ii. De Zalze Golf Club
iii. Holiday Lodges
iv. HOA Offices, pumps, street lights and workshops
v. 4 18 houses
Although, the purchase tariff from Eskom was time/price
differentiated, prior to Apr 20 13, the De Zalze's
consumers were purchasing electricity at a single flat rate
regardless of the time of day or season. There was
therefore a total disconnect between the price signal that
the residents experienced and the pricing structure from
Eskom.
The Eskom Time of Use periods are shown in Figure 1.
- ".,.
_ Off.....
Figure I. Eskom's Time-of-use Tariff Periods
3 ELECTRICITY PLAN AND OBJECTIVES

2. The specific interventions that were launched at the Estate
by the HOA Board were:
D'l1E INTER.1'III11G1 S4'ETlDClJ11D>1E a:MMINlS
2012 Ina-eased winter • Improvement of I--IQ.! • The conventional meters
and decreased �-flow during winter gill read only total
summer tariffsto months volume conrumed at
match !:skom's month end
ta-iff profile
2012 Eskom's • FEduced consumption • ,Approximately 50
Fesidential Mass hOlJ,a,e>dspa:tidpated
Fbllout offered
l..8)dONnlighters,
�timersand
showerheads
53p InstailEtion of • Fenote meter reading • Snart meterswere
2013 sma1 meters • Internet access to installed ald paid by the
consumption fD'
• Feverse metering for • Meter-reading contract
sola installations terminated
• Efficient management of
electricity
• Improved meter
axuracy
Nov Po:::eptmceof • l..o'vver purchase cost of • FesidentsWeI'e asked to
2013 Q-itical Peak C3y electricity from E:kom reduceconsumption on
Ta-iff Riot from critical Peak 03ys, but it
E:skom on the did not affect their
ESkom purdlase individual acx::ounts
ta-iff
Apr Introduction of • Encoura:Jeshifting of • Bectricity isdl�
2014 lime of l...Ise taiffs consumption out of peel< outside the peak hours
to all userson the hours • lDw volume consumers
EState no longer subsdise hi!tl
volume consumers
• Consumerswho mitt
consumption ENrIErffrom
peak hours, reducetheir
own oost and it h85M
impact on the overall
purdlase oost from E:kom
• Consumersere able to
monitor their
consumption patternson
the internet
Apr Induson of Qitical • l..O'...ver oost of electricity • Lower pricefa- 348 days
2014 Peak C3y Impact to those residentstha of the y",," with hig,
on tariffsto all respond to the pricing pricing for the other 17
userson the Estate sgnal Qitical Peak cays. E:kom
gves24 hours noticeof a
CFD
Early GJidelines • Fedudion in electricity • ::et of technical ,
2015 available for photo purchases from E:kom commercial and aesthetic
'vOltaic installaions
5 RESULTS
5. 1 RELATIVE REDUCTION OF ELECTRICITY
COST
Figure 2 shows the average purchase price of electricity
from Eskom compared to the average price paid by a
resident at De Zalze and prices paid by City of Cape
Town and Stellenbosch residents. The prices were
calculated using the average De Zalze resident's
consumption as reference. The following comments can
be made in relation to the interventions listed in Section 3:
• The De Zalze's prices stayed more or less the same
since 20 12/13 compared to the current level when
compared to the other prices, mainly because:
o Lower purchase cost due to load shifting,
probably as a result of geyser and pool
timers
o Introduction of Critical Peak Day (CPD)
Pricing
o Increased energy efficiency awareness
• The reduction in price from 20 131 14 to 20 14115
could be as a result of:
o Residents' response to the Time of Use
pricing signal which was introduced in April
20 14. Many residents introduced timers on
their geysers and undertloor heating which
had a considerable impact on the winter load
profile
o The inclusion of the Critical Peak Day
Pricing in the end-user tariff to residents
Table 1. Summary of electricity interventions Residential Cost ofElectricity per kWh calculated
4 EVALUATION PARAMETERS
Specific measurable parameters have been identified to
evaluate the impact of the interventions discussed above.
These are:
•
•
•
Measurement of electricity cost:
o Total consumption trend
o Average Eskom purchase price
o Average price to the De Zalze consumer
in comparison with City of Cape Town,
and Stellenbosch Municipality
o Peak % consumption trend
Improved energy efficiency
o Reduced total consumption
o Reduced average monthly consumption
Reduced impact on the environment
R 1.60
for the average monthly consumption
R 1.40
R 1.20
�
R 1.00
� R 0.80
�<.J R 0.60
R 0.40
R 0.20
R 0.00
2009/10 2010/11 2011/12 2012/13 2013/14 2014/15
Figure 2. Average residential cost of electricity per kWh for the
average De Zalze consumption.
The total Estate consumption profile for the 5th
February 20 15 is shown in Figure 3. Note the reduced
consumption during the evening peak between 18:00 and
20:00. It can also be seen that load shedding took place
between 14:00 and 16:00. Only the peak areas are
highlighted in the graph and the standard and off-peak
areas are not separated.

3. TOTAL ESTATE CONSUMPTION PROFILE
1600
1400
1200
1000
800
600
400
200
00:00
5102
04:00 08:00
5102 5102
12:00
5102
Time
16:00
5102
20:00
5102
Thu Feb 05 2015 00:00 to Fri Feb 06 2015 00:00
Figure 3. De Zalze overall consumption daily profile
00:00
6/02
The reduced peak consumption is even more evident
in Figure 4 for one of the Villages of the Estate for the
same day. The effect of geyser timers that come on at
03:00 can clearly be seen as well as the recovery after
load shedding.
VILL AGE CONSUMPTION PROFILE
140
120
100
80
60
40
20
00:00 04:00
5102 5102
Time
00:00
6/02
Thu Feb 05 2015 00:00 to Fri Feb 06 2015 00:00
Fig.ure 4. A Village consumption daily profile (one of many)
The consumption during peak hours has reduced
slightly over the past few years as can be seen from
Figure 5, but this is expected to get better as more
residents become aware of the benefit of shifting
consumption out of peak periods. Peak hours make up
14.8% of the total hours in a week. Some residents have
already achieved a peak percentage of below 10%.
Total Estate peak usage as % of total
18.40%
18.20%
18.00%
17.80%
17.60%
17.40%
17.20%
17.00%
16.80%
16.60%
2009/10 2010/11 2011/12 2012/13 2013/14 2014/15
Figure 5. Total residential peak usage as % of total consumption
(morning and evening peak)
The effect of reduced peak consumption on the
average cost of electricity is shown in Figure 6 and it is
obviously much more beneficial during winter months. A
peak reduction from 22% to 9% of total consumption, will
reduce the overall average price in winter by 27% and by
14% in summer.
�
.
Co
t:
0
U
Estate Electricity Cost per kWh vs Peak % Consumption
RO.80
RO.70
RO.60
i
! Difference
j
---------------------------------t------------------..J
mm---m-m-m----------f--------------------J 1Dlff
���""
Peak % Consumption
-Cost per kWh (Summer) -Cost per kWh (Winter)
Figure 6. Total residential peak usage as % of total consumption
The time of use periods for De Zalze are shown in Figure
7.

4. Figure 7. De Zalze Time-of-use Tariff Periods
The Eskom Standard and Off-peak periods have been
combined into one Off-peak period for the Estate to
simplify the tariff.
5.2 ENERGY EFFICIENCY IMPROVEMENTS
The measurement of energy efficiency improvement on
the Estate is viewed through the trend on the overall
annual electricity consumption on the De Zalze and the
average monthly consumption of individual residents.
De Zalze's electricity consumption, excluding the wine
cellar, is shown in Figure 8. It has decreased from a peak
of 8 927 MWh per year in 20 101 1I to 7 967 MWh in
20 141 15. This is a reduction of 10.8% despite an increase
in metered consumers from 403 to 4 19 for the same
period. In addition, the average consumption per resident
per month has reduced from 1846 kWh in 20 101 1I to
1585 kWh in 20 141 15 or by 14.2%.
The reasons for this can most probably be attributed to:
vi. More awareness of electricity consumption and cost
vii. Deliberate energy efficiency improvements such as,
solar water heating, heat pumps, LED and CFL
lighting, geyser timers, shower heads, etc.
Estate Annual Residential Electricity Consumption
8600000
8 400 000
8 200 000
8 000 000
7800000
7600000
7 400 000
7 200 000
7 000 000
6800000 I I2009/10 2010/11 2011/12 2012/13 2013/14 2014/15
_ Estate Total Residential Consumption
-Average Residential Consumption per month
1800
1700
1600
1 500
1 400
1 300
1 200
1 100
1 000
Fig. 8. De Zalze total annual residential consumption and
average monthly residential consumption trends
6 CONCLUSION
This analysis indicates that the De Zalze Estate is on the
right track with its energy management programme. The
main challenge is to get wider participation by more
residents in response to the electricity pricing signal. It
seems that only 25% of the Estate's residents are
responding to electricity prices and energy efficiency
ideals at this stage. The possible reasons for this could
include:
viii. Electricity is seen as a necessary commodity,
whatever the price.
ix. Electricity is Eskom's problem
x. Insufficient understanding of potential solutions
xi. Low priority item
The challenge is to increase awareness of the
environmental impact that electricity generation from coal
has in this country. The delays in the commissioning of
Medupi Power Station, the Eskom load shedding crisis
and electricity increases certainly helps to increase
awareness of the increased scarcity of electricity, but
unfortunately in a negative sense.
The ideal world for the Estate would be:
xii. Control all geysers, pool pumps and underfloor
heating to switch off during peak times
xiii. Widespread installation of photo voltaic systems and
UPS
xiv. Heat pumps or solar water heating
xv. Consideration of gas for cooking
xvi. Energy efficient lighting everywhere
xvii. Efficient ceiling insulation at all houses
Economic considerations will not be the driver for the
introduction of PV systems at De Zalze as a result of the
low electricity price on the Estate, but will rather be
driven by the need to overcome the effects of power
interruptions and environmental awareness.
ACKNOWLEDGEMENTS
6. 1 The De Zalze Estate Board for allowing me to use
the information from the actual results in this
presentation
6.2 Gateway Utility Solutions for the sponsorship of
the presentation at the conference
REFERENCES
[I] Stellenbosch Municipality, 2009 to 20I5, schedule of electricity
prices
[2] City of Cape Town, 2009 to 2015, schedule of electricity
prices
[3] Eskom Tariffs, 2009 to 2015, schedule of electricity prices
[4] De Zalze Estate, 2009 to 2015, schedule of prices
[5] De Zalze Estate, 2009 to 2015 electricity consumption data

5. AUTHORS BIOS AND PHOTOGRAPHS
Corrie Visagie is currently with the energy
management company, Gateway Utility
Solutions and has extensive Eskom experience
in telecommunications and protection, project
management, construction, sales & marketing,
customer service, key account management,
electricity pricing and energy management. His
current focus is on energy management,
metering and electricity pricing.
He obtained an honours degree in electrical engineering (1973), an
MBA (1993) from the University of Stellenbosch and a Government
Certificate of Competency in electrical engineering.
He enjoys a game of golf and used to be a keen tennis and table
tennis player. Corrie is married to Estelle, and has two sons, a
daughter and three grandchildren.