SA Affordable Housing May - June 2020 // ISSUE: 82 | Page 24

PROJECT
Saving millions on water
heating a Wits Junction
By Eamonn Ryan
The first of its kind, the Wits Junction district heating project, combines
solar, co-generation and gas heating technologies, servicing 14 student
residence buildings for the University of the Witwatersrand with hot water
from one centralised hot water plant room. Installation includes 600m 2 solar
heating plant with 10m 2 Austrian-manufactured collectors.
ALL IMAGES BY SANEDI
“The previous domestic systems were distributed
systems on multiple roofs; the new solar layout is on
one central roof,” explains Wally Weber of BlackDot
Energy, one of the project developers. “A combined system
uses the advantages of each technology: solar has a very low
running cost, while CHP (combined heat and power) gives
continuous base load coverage. The combination covers
thermal and essential electrical loads.
“There are 1 103 students in the 14 buildings, with an
average consumption of 94 000l of hot water per day.
Peak demand is in the morning, averaging 30% of daily
consumption, with a maximum demand of 28 200l in an
hour. The system supplies the entire hot water demand,
including kitchens, laundry, cleaning and other domestic uses.
Each student has his/her own kitchen and there are some
centralised service rooms for cleaning staff.
“Since the system was commissioned, the complaints of
not having hot water have reduced by 98%. The redundancy
design guarantees supply, also during maintenance periods.
Dr Karen Surridge, Centre Manager, Renewable Energy Centre of
Research & Development, SANEDI.
A SOLTRAIN system at Klein Karoo International leather tannery in
the Northern Cape.
“The estimated costs savings are R40-million over
the next 20 years and already the University has seen
substantial electricity savings over the trial period of eight
months. As the electricity cost from the co-generator is
equal to municipal cost, the thermal energy is free and
the centralised plant requires a lot less maintenance
intervention, hence less costs. There is currently a back-up
water system installation in progress, with 300 000l tanks,
and a more advanced logging and measurement system is
also planned.
“The system has been a major success in not only meeting
financial and energy saving parameters but also the service
delivery levels have vastly improved. The small interruptions
are from water interruptions from municipality or ring
main circulation pumps blocked from debris in the water.
Unlike previous systems, this project comes with integrated
monitoring and maintenance from the very first planning day,
moving us towards energy 4.0.”
The design team combined BlackDot Energy, DSB and
Holms and Friends, with BlackDot Energy as project leader
and appointed engineering company. Holms and Friends did
the solar construction.
22 MAY - JUNE 2020 SAAffordHousing saaffordablehousingmag SA Affordable Housing www.saaffordablehousing.co.za