Figure 1. Two Rivers Mall Kenya. Source – Construction Kenya
Among your weekly errands is probably visiting a store in a mall. In Nairobi especially, standalone shopping stores are becoming fewer as investors are betting on adding to the already-present 30 malls. From the convenience of having many shops in a single location, to enjoying the buzzing ambiance of the recreational areas, malls have found a special place in every Kenyan’s heart. This is not all rosy however. Despite massive investments in the country’s real estate sector, the returns have not matched the monetary input. For one, Kenya’s electioneering cycle has far-reaching effects on the economy, including affecting the health of mall businesses.
Other than the political situation, energy is yet another key component to the profitability of a mall. Tenants usually require energy dependent utilities such as electricity, water, gas, and compressed air so as to attract and close on a customer.
What is the energy mix used in malls in Kenya?
From air conditioning to lighting, elevation systems to air conditioning, malls are silently consuming large amounts of energy to make for an exquisite experience.
Common challenges faced by malls
With regards to energy management, investors will heavily rely on the expertise of the contractors to balance the expense of efficient equipment with the investment budget. The common hurdles faced by mall energy management teams include: 1. High lighting costs 2. High air conditioning costs
3. Need for voltage optimization 4. Low overall power factor 5. Unbalanced voltage and current 6. Poor BMS system
Let’s delve into each one of these issues and how you can deal with them.
The wide range of shops and amenities in malls require different lighting fixtures to create ambiances that attract and relax customers. The variation can include incandescent and halogen LED lights. Renters might focus more on ambiance than being energy sensitive, and this is still debatable. Take the example of a coffee shop that only uses incandescent bulbs (60W) for each of its 30 lounge tables. The shop operates 12 hours daily, all year round. A competitor’s shop on the other side of town has instead chosen to use 7W LED bulbs for the same space. The difference in their spending is shown in the following table:
|Fixture type (30 units)||60W Incandescent||7W LED Bulb|
|Initial cost||KES 2,400||KES 12,000|
|Annual electricity bill (KES20/Unit)||Ksh. 157,680||Ksh. 18,396|
|Bulbs required for 25,000 hrs of operation (3 years)||120||30|
|Total spending every 3 years||Ksh. 477,840||Ksh. 67,188|
|Total spending every 5 years||Ksh. 795,600||Ksh. 103,980|
Spending illustration with graph
Figure 2. Running costs of different light fixtures
Heating Ventilation and Air Conditioning (HVAC)
The HVAC systems in malls are large scale and can either be centralized to a control unit or distributed and managed separately. Distributed systems have proven to consume less energy because they can be managed separately and easily adapt to the demand of the mall faster. Areas such as bakery sections, fridges, restaurants all need temperature control to make it conducive for people to work or relax.
Figure 3. Ventilation system. Source – AnOfficeSystems
Three ways to increasing your HVAC efficiency are: 1. Using a Variable Refrigerant Flow (VRF) system 2. Using geothermal systems 3. Switching to rooftop systems
Variable Refrigerant Flow (VRF)
Many buildings today use a HVAC system that consists of a connected evaporator and condensing unit for use in a particular place. Should more areas need air conditioning, more ductwork will be needed. This often has the shortcomings of being energy inefficient and inflexible to expansion. VRF on the other hand uses one condensing unit and connects it to several indoor fans in a building. The whole arrangement can either be a two or three-piped system. Two-piped systems ensure that at any instance, all the fans can either be heating or cooling the room. On the other hand, three-piped systems ensure that at any point, some fans can be heating one room, while the others cool another. Coupled with a Variable Speed Drive (VSD) to control the compressor speed, significant energy savings can be realized.
These systems use the earth either as a heat source or heat sink depending on the season. An antifreeze fluid is circulated into the ground using tubes that allow heat transfer. The fluid is then used in a heat pump to provide heat especially in cold conditions, and it has shown an improvement in the pump’s Coefficient of Performance (CoP). Using geothermal systems for commercial settings has been found to save about 40% of annual air conditioning expenses. The plumbing of these systems can be installed vertically, horizontally or in a pond.
Rooftop HVAC units
These are relatively low cost investments that optimize on the valuable floor space of a building. The US, for example through the Department of Energy, has pushed programs like the Advanced Rooftop Unit Campaign, to encourage facilities to replace their old rooftop units with newer more efficient ones. Of central focus is the move to motors driven by Variable Speed Drives (VSDs). The results? A number of buildings have recorded up to 50% reduction in their energy expenses.
In many instances, the utility company will supply large consumers with voltages in the higher end of the required parameters (e.g more than 425V in Kenya) because they are still using old distribution networks. The supply might also be this way to account for any voltage drops.
However, higher-than-necessary phase voltage causes many single and 3 phase equipment to be energy inefficient due to higher power consumption. Mechanical equipment such as compressors and induction motors are likely to have overheating problems, resulting in higher maintenance costs. Figure 4. Voltage Optimization. Source – Captech
By including voltage optimizers in series with your distribution, the supply voltage to loads is reduced to suitable values. In Kenya, phase to phase electricity is supplied at 415V/240V, but optimum voltage for loads is 380V/220V. Voltage optimization units are installed parallel to your distribution board. There are two modes of operation: 1. Fixed – where all incoming voltage is optimized by a set ratio 2. Dynamic- sensors detect the line voltage and optimize it to a set value More on voltage optimization can be found here
Power factor correction
3 phase equipment like pumps and compressors are inductive loads which can have poor factors. Most prominently, poor power factor, typically below 0.9, results in the utility adding a power factor surcharge cost on your bill. Other effects of low power factor are decreased voltage at the load and increased copper losses. Installing power factor correction banks in your supply has the following advantages: 1. Reduced/eliminated power factor surcharge penalty 2. Lower demand charges – Higher power factor comes as a result of low measured kVA. The utility will therefore charge less for the demand power 3. Better voltage across the line as a result of reduced current More on power factor correction is here
Voltage, Current unbalance
Behind the scenes, malls rely on both single phase and 3 phase equipment for day-to-day operations. These pieces of equipment will start and stop at differing times, having varying demands on start and stop cycles. Without appropriate measures of organizing and balancing loads across phases, your facility risks running into voltage and current imbalance problems. The most common effect is equipment de-rating which increases copper losses and reduces performance. Measures that can be taken towards establishing balance are: 1. Arranging single phase loads so that there is a balance on all three phases. 2. Reduction of harmonics by introducing active or reactive filters in your supply. The filters introduce current waveforms which counteract negative currents in the supply. 3. Replace motors with high and unbalanced phase reactance 4. Installing an energy monitor that will send you alarms when there is an unbalance of current or voltage outside the set parameters More on this can be found here
Poor Building Management Systems (BMS)
Malls usually feature many amenities and therefore attract huge traffic, especially over weekends and during holidays. Effective management of bulk systems like power supply, HVAC, emergency response, alarms, and lighting requires a robust system that can shrink everything to a handful of control panels. Enter Building Management Systems (BMS).
BMS is a centralized system for monitoring and control of a building’s electrical and mechanical installations like lighting, HVAC, security, and alarms. Schneider Electric proposes energy savings of up to 20% for malls that have a BMS. Figure 5. Building Management System. Source – MLN Company
Advantages of such systems are: 1. Easily monitor and control various processes 2. Get reports on the energy/water/gas/compressed air consumption trends of the facility or individual equipment 3. Alarms to notify you of any failures More on BMS can be found here
For malls, energy management will translate to higher margins and better services to the occupants. Adhering to Kenyan regulations, it is important to conduct energy audits and follow through with the recommendations to improve your facility performance. Therefore, energy monitoring should always be in your long-term plan so as to gain valuable insights into your building performance and access predictive analysis on how to improve.
Facilitiesnet – Understanding Rooftop HVAC Units as an Energy Saving Option Standard Media – Mixed Use Developments Hold Hope For Real Estate Business Daily Africa – Why Malls in Kenya are not Doing That Well Mid-Atlantic Controls Corp.- Energy Management Problems in Shopping Malls South China Morning Post – Audit Shows Huge Differences in Electricity Use among Malls and Offices