- Introduction:
When selecting electrical capital equipment, such as transformers and generators for commercial buildings, the typical practice is to base decisions on a demand load of 0.8kVA to 1.0kVA per 100 square feet. This is often stipulated in Request for Proposals from multinational corporations and follows base building specifications provided by developers for IT and ITes spaces (excluding labs and data centres).
However, energy audit studies conducted on completed or operational projects reveal a significant disparity between designed load capacities and actual consumption. In Hyderabad, during peak summer months like April, May/ June, maximum consumption has been recorded at only 0.5kVA per 100 Sft. On average, the annual demand load has not exceeded 0.4kVA per 100 Sft of leasable area, prompting a reconsideration of the capital equipment’s sizing.
- Impact on Project:
When projects are designed based on higher-than-necessary kVA per square foot requirements, it has several negative consequences, both technically and financially:
- High Minimum Demand Charges: Overestimating the demand load and committing to higher capacities results in larger contracts with electricity supply companies, leading to inflated minimum demand charges. These charges must be paid even if actual consumption is much lower than the contracted amount.
- Substation Requirements: Larger developments might require additional electrical substations to accommodate the over specified demand load. This adds complexity to the electrical infrastructure and increases both the initial capital expenditure and long-term maintenance costs of the project.
- Underutilized Equipment: When transformers, generators, and other major electrical equipment are oversized, they operate below their optimal capacity. This leads to inefficiencies and a higher cost per unit of electricity generated. It also ties up capital in equipment that is not being fully utilized.
- Higher Maintenance Costs: Over-specified equipment incurs higher maintenance costs, even though the actual demand does not justify the size of the equipment. The cost of maintaining these larger systems is proportionately higher, resulting in unnecessary operational expenses.
- Load Pattern and Technological Advancements:
Modern office buildings are increasingly adopting energy-efficient technologies, which help to reduce overall electrical consumption. These changes include:
- Energy-Efficient Lighting: The transition from traditional lighting solutions to LED lighting, particularly in common areas and basements, significantly reduces the electrical load associated with lighting.
- Low Power Computing Devices: With the shift towards low-power computing devices such as energy-efficient desktops, laptops, and servers, the overall energy consumption for computing tasks has decreased.
- Efficient Mechanical Equipment: Advances in mechanical systems, including more energy-efficient Air Handling Units (AHUs), fans, and chillers, have lowered the power required for heating, ventilation, and air conditioning (HVAC) systems.
- IE3/IE4 Motors: The use of high-efficiency IE3/IE4 motors in lifts, plumbing systems, and ventilation systems further contributes to energy savings by reducing the load on mechanical equipment.
- Power Consumption Trends:
Here’s a breakdown of how these advancements in technology have impacted load reduction:
| Equipment/System | Old Technology | Load Considered (VA/Sft) | Advanced Technology | Load Considered (VA/Sft) |
| Water-cooled Chillers & Pumps | COP – 5.8 | 1.9 | COP – 6.3 | 1.5 |
| Ventilation/Pressurization Fans | Efficiency 2.0 | 0.3 | IE – 3 | 0.25 |
| Plumbing & STP Pumps | Efficiency 2.0 | 0.3 | IE – 3 | 0.25 |
| Common Area Lighting | T5 / T8 Lighting | 0.15 | LED Lighting | 0.11 |
| Lifts with VFD | Efficiency 2.0 | 0.3 | IE – 3 | 0.22 |
| Overall Power requirement for Office space | 2.95 | 2.33 |
These trends show that connected loads are decreasing from 0.8kVA per 100 Sft to 0.6kVA per 100 Sft, with actual demand loads being even lower by considering the average load consumption analysis of prevailing building analysis which is closer to 0.5kVA per 100 Sft.
- Capital Equipment Selection:
For a commercial building with a leasable area of 1 million Sft, the appropriate sizing of capital equipment is critical. Historically, equipment is selected for higher load scenarios (0.8kVA per 100 Sft), but with actual loads trending lower, there is an opportunity to optimize capital equipment selection.
A case study for 1 Million sft is mentioned below for better understanding purpose.
| at 0.8 KVA / 100 Sft | at 0.6 KVA / 100 Sft | Reduction details | ||||||||
| S no | Description | Load in KVA | No of transformer and rating required with 80% loading of transformers | No of DGs and rating required with 80% loading of DGs | Load in KVA | No of transformer and rating required with 80% loading of transformers | No of DGs and rating required with 80% loading of DGs | Load in KVA | No of transformer and rating Reduced | No of DGs and rating Reduced |
| 1 | 10,00,000 Lakhs Sft Leasable area | 8000 | 5 Nos x 2000 KVA | 5 Nos x 2000 KVA | 6000 | 4 Nos x 2000 KVA | 4 Nos x 2000 KVA | 2000 | 1 Nos x 2000 KVA | 1 Nos x 2000 KVA |
Over and above equipment reduction mentioned, the use of super ECBC/ECBC-compliant transformers, which adhere to the highest efficiency standards, can also minimize energy losses.
- Additional Tips:
Currently, UPS systems in many IT offices are still being sized based on an outdated standard of 150 W per computer system. This approach no longer reflects the advancements in technology. Modern desktop computers, as well as all-in-one devices where the monitor and CPU are integrated, now consume significantly less power, often below 100 W. Moreover, many IT companies are moving away from using desktop computers entirely and are instead switching to laptops, which come equipped with their own inbuilt batteries, reducing their reliance on UPS power.
Given these developments, there is a clear opportunity to reassess and optimize UPS capacity for IT offices. By conducting a thorough analysis of current hardware usage and power needs, companies can design more efficient, customized UPS systems tailored to their specific needs. This could lead to a substantial reduction in UPS capacity, which would have several benefits. First, it would simplify the overall electrical distribution to individual workstations. Second, it would reduce the amount of ground cabling required, as well as the number of distribution boards (DBs). Third, by lowering the load on the UPS, companies could also reduce harmonic distortion, improving the quality of power supply across the office.
This optimization would result in cost savings not only in terms of hardware (smaller UPS units, less cabling, and fewer DBs) but also through lower operational costs related to energy consumption and system maintenance.
This elaboration focuses on the key points of updating UPS calculations and the positive outcomes of tailoring designs to modern equipment trends in IT offices.
- Conclusion:
Given the ongoing reduction in load trends due to the adoption of high-efficiency systems, it is advisable to plan space and electrical infrastructure based on a design load of 0.8kVA per 100 Sft. However, capital equipment should be procured and installed for a lower demand load of 0.6kVA per 100 Sft. This approach allows for modular scalability—additional equipment can be added only when required based on future demand growth. By optimizing equipment sizing, projects can achieve substantial cost savings in capital cost, installation, energy consumption, and long-term maintenance.
