STANDARD BANK Braamfontein
KAYEMA Energy - Hybrid 200 m2 Solar Thermal System
TOTAL M2 Panels 200
Tank Storage 48 000
Year Commisioned 2010
Tank Construction Stratifiedd vertical
High / Low- Pressure Storage High pressure
Litre / m2 240
Energy Savings / Annum kWh 438 000
SHORT DESCRIPTION OF THE SYSTEM
Kayema Energy Solutions completed one of the largest hybrid hot water systems in Southern Africa for Standard Bank building in Braamfontein. The building forms part of the cluster of buildings in the CBD of Johannesburg and boasts an employee count well within the thousands.
The hot water supplied by the system ensures that the 24-hour gym facility is supplied with hot water at all times for its large staff complement. The system utilises solar thermal, heat pump and electrical technologies as heat sources with a complex cascaded storage system, all monitored by an online control system.
CAPACITY AND UNIQUE CHARACTERISTIC’S OF THE SYSTEM
The sheer size and complexity of the hybrid system earned Kayema both a win and nomination of the prestigious Southern African Association of Energy Efficiency Energy Company of the Year Award in the years of 2010 and 2011 respectively.
With 48 000 litres of hot water produced daily, the commercial building saves up to 1MWh of energy every day. The total collector size exceeds 100 panels, for which custom permanent standards were designed specifically. The secondary heat source is also energy efficient; industrial heat pumps with a combined capacity of 40 thermal kilowatts are programmed to increase water temperature. As a final fail safe, stratified storage tanks include electrical elements for day night time and poor solar radiation. The performance of the system is tracked and reported to stakeholders regularly.
The difference between the above graphs shows the extent of the savings experienced by Standard Bank (based on actual measurements)
The system uses external heat exchangers which transfer heat from the solar fluid to potable water. For this reason, it is important to ensure that the plant room in which the exchangers are located is well insulated to avoid heat loss. Extensive piping lengths were given careful attention in terms of insulation and sizing, especially to maintain the pressure and manage the expansion and contraction of the heating fluid. Circulation pumps form an important part of the system in terms of function and control; drastic ambient temperature drops trigger pump circulation to ensure the solar fluid does not freeze and cause catastrophic damage to the solar panels. These are just a few features of the complex system.
The panel stands have proven sturdy during extreme weather experienced since installation, as have the high quality flat plate collectors used as panels. Regular cleaning, and maintenance of every valve, bend and pipe is imperative to ensure that system continues to deliver the highest savings possible. The key temperatures, flow rates and pressures on the system are fed into the building management system. The client is thus able to set alarms triggered by sudden conditions. This also ensures easy trouble shooting of rather complicated system!
The storage element of the system is key in order to maintain the system efficiency. The cascading arrangement used ensures that lower volumes of water are heated incrementally. The vertical nature of the tanks makes use of natural stratification, by drawing hot water from the tops of tanks. The tanks are all well-insulated, thermostat controlled and located in the plant room directly under roof that house panels. Each storage tank can easily be isolated and bypassed to allow for easy maintenance, and for energy to be saved when demands for hot water are extremely low. For example, one might bypass one of the tanks during the December period.
CONTACT INFORMATION:Adhila Mayet Tell: 011-706 33 33