Business Case for PQ Investment by Commercial Buildings

Published On: Sep 14, 2014


According to total electricity sales (as per 2011-12), around 54% of the energy produced in India is used to power end-customers like industries (~ 44%) and commercial buildings / establishments (~10%). In today’s scenario, while electronic / digital based equipment increases productivity, this type of equipment can often either be adversely affected by poor power quality or be the cause themselves to impact the power quality environment. PQ issues have significant economic consequences for these end customers (Staggering loss of INR 1000 billion as per the study undertaken by Wartsila India, 2009 ). Industrial customers in India are gradually moving ahead towards adoption of PQ solutions due to their technical knowhow; however the situation is not same with commercial customers, generally governed by complete outsourcing culture. PQ is becoming an important issue for commercial customer segment also (in addition to industrial customer). Commercial establishments can be better prepared for handling PQ issues if proper steps are taken during inception, thus cutting down huge losses caused by PQ problems during operational periods.

The intent of this blog is to show how power quality impacts commercial equipment/customers and what mitigation techniques and solutions can be applied to minimize shutdowns and equipment damage. The term commercial building primarily includes IT/ITeS offices, high rise apartments, malls, air, railway and bus terminals, etc. (except industrial buildings, private dwellings)

KEY ELECTRICAL LOADS IN COMMERCIAL BUILDINGS

Before we move ahead to recognize the impact of poor PQ, let us first understand the key electrical loads in the commercial buildings. Fig. 1 depicts the electrical energy end uses for US Commercial sector:

It can be seen from the above figure that the largest commercial building electrical load isHeating, Ventilation and Air Conditioning / Cooling (HVAC) System (around 39%), followed by Lightning (23%), Office Equipment (18%)and others. In India and other countries also,HVAC and lighteningserves as the two most energy consuming end-use applications within a building.

FREQUENT INTENSIVE PQ DISTURBANCES AND ITS IMPACT ON COMMERCIAL BUILDINGS

With the extensive application of sensitive power electronic equipment like VSDs and non-linear loads like CFL, electronic choke, SMPS based systems etc in commercial buildings, various problems like power surges/sags, poor voltage and frequency regulation, harmonics, switching transients, electrical noise and Electro Magnetic Interference (EMI) effects are frequently encountered which leads to poor power quality. The actual PQ problem of commercial building varies, depending on its electrical characteristics like the systems, energy sources, equipment, etc. Some of the key physical manifestations of the PQ issues are mentioned below:

Equipment affected due to poor PQ

External Manifestation of poor PQ

Electrical PQ problem

Air Conditioning / HVAC equipment

Premature compressor failure

Voltage variation

Lighting  control

Flickering / fluctuations of lights, unit damage

Transients / voltage variation

Data processing

Data loss / data error / data corrupt

Voltage variation

Digital Scale / Thermostat

Unit damage

Transients / EMI

Fire / Security System

False alarms, unit damage

Transients / EMI / voltage 
variations

Computerized equipment

Unit damage

Transients

Copy machine

Touchpad damage

Transients

Bar code scanner

Scanner damage

EMI / Transients

Energy Management

Loss of control

Transients

Table 1. Impact of PQ Disturbance on Commercial Sector Electrical Equipment

It can be observed from above table that PQ variations affect different electrical equipment. However, depending on the criticality of the equipment affected, the consequence of PQ disturbance may range from a minor nuisance to extensive equipment damage and loss of critical data, or even an extreme case of fire accidents. For example, a momentary voltage dip may impact the operation of an elevator and may cause it to stop at a floor where it isn’t supposed to stop or not stop at right level. In most cases, this is nothing more than a nuisance. However, the same voltage dip might instead cause an elevator controller to fail and may require a service call during which the elevator would be unavailable.

One of the major PQ problems in modern buildings is the harmonics which takes the form of current as well as voltage harmonics. This is, as a result of increasing number of non-linear loads connected to the circuits in the building. Majority of harmonic problems affecting a building are generated within the building. Computers (the highest polluter), printers, lightning equipment and other power electronic equipments are some of the main sources of such problems. The presence of harmonics in such buildings not only affects themselves but also adjacent customers.

As per the survey conducted by International Copper Association Southeast Asia in 2012 in three countries (Indonesia, Thailand, Vietnam), one of the key results indicate that ‘Equipment damage’ is the main component of the PQ cost in the commercial sector, which is like 46.5% of the total cost . (See detailed report –Power Quality Loss Survey Report)

Hence, it is very critical and important to take into consideration as many precautions as necessary to minimize possible PQ issues. This requires advanced planning and sometimes, additional capital. Above mentioned PQ related issues can be effectively mitigated by applying the following techniques by the developer/builder:

  • Design of electrical systems with optimum sizing, right derating and adequate redundancy.
  • Application of passive, active and hybrid harmonic filters not only suppress harmonics, they also help to reduce the electricity demand by increasing the power factor.
  • Voltage compensators are used to regulate voltage, power factor, harmonics and stabilizing the system.
  • With proper designing of the power supply system and load equipment, PQ problems can be brought down
  • Uninterruptible power supplies (UPS) provide alternative power source, supplying continuous and conditioned power to connected equipment to mitigate a power interruption or fluctuation.
  • Lighting arresters are used for eradicating large over voltages as well as high energy levels
  • Other solutions can be using special transformers like isolation transformers, ferroresonant transformers, tap switching transformers, line voltage regulators, power conditioners, etc.

WHY THERE IS NEED OF ADOPTION OF HIGH PQ APPROACH IN TODAY’S INTELLIGENT / GREEN BUILDINGS

The building sector is one of the biggest emitter of Green House Gas (GHGs) in India. Of the building sector, commercial building accounts for nearly 33% of these emissions. There are vast opportunities to reduce electricity consumption and increase energy efficiency within commercial buildings. Today’s new buildings use hundreds of pumps and fans to control heat, cool the air, and pump fresh water.

In a study by United Nations Development Programme (UNDP), under the title ‘Energy Efficiency Improvements in Commercial Buildings’, it is estimated that new buildings can reduce energy consumption on an average between 20-50% by incorporating appropriate design interventions across the key electrical components.

  • Envelope (walls, roofs and windows), heating, ventilation and air-conditioning (HVAC, 20-60%),
  • Lighting (20-50%),
  • Water heating (20-70%),
  • Refrigeration (20-70%) and
  • Electronics and other (e.g., office equipment and intelligent controls, 10-20%).

For new commercial buildings, Bureau of Energy Efficiency (BEE) has developed Energy Conservation Building Code (ECBC). The purpose of ECBC is to provide inputs to the energy efficient design and construction of buildings. The ECBC sets minimum energy standards for buildings (residential and commercial) to provide information on how to design energy efficient buildings. In one of the recent developments (i.e. September 2014), BEE has released new guidelines and regulations for energy efficient buildings; however this does not discretely address or considers PQ. Most commercial buildings in India have an Energy Performance Index (EPI) of 200-400 kilowatt-hour (kWh) per m² per year, while similar buildings in North America and Europe have EPI lower than 150 kWh per m² per year. Energy-conscious building design has been shown to reduce EPI to 180 kWh per m² per year (national benchmark) and is considered as ECBC compliant. Some of the case studies (refer reference #2 for details) employing environmentally sensitive designs lead to savings of the order of 20-50%. Initial investment cost will increase by 10-15%, with payback period varying from 3 to 7 years 

Generally, a developer looks forward for quick return on investment (RoI). According to Frost & Sullivan report on Bright Green Buildings in 2008, cost of an intelligent building is often not that much higher than conventional structures. Certain aspects associated with intelligent technology such as cabling, labour costs are actually less costly than traditional infrastructure. However, other technologies and equipment will require additional investment to integrate all of the components of the system. For example, integrating the access controls system with lighting and HVAC systems will cost more up-front than installing disparate systems alone.

In a new structure, the project costs incurred include the design and build phase of its life cycle, however it reduces resource consumption during the design phase by using active and passive methodologies. This can remarkably bring down HVAC requirements, thus reducing both capital and operational costs. Additionally, minimisation of equipment and cabling can be reduced by integrating control as well as power systems, viz safety, lighting, HVAC etc. Integrated building management system infrastructure could help save around 33% on labour as well as material costs. Judicious control of present HVAC equipment can help save in operation and management costs up to 30%. Summarizing, it reports that entire life cycle cost of an intelligent building is lower to the conventionally erected and operated one and has short RoI compared to traditional/modern building

CASE STUDY 1

  • Intermittent Equipment Disruption : Process Restart or “Do Over” Required
  • Random Equipment Lockup : System Reboot and Recalibration Required
  • Equipment Lockup Every Time Electrical Supply Transferred Between Utility and Backup Generator-Set : System Reboot and Recalibration Required
  • Intermittent Image Problems with Monitors, Including Changing Colors and Distortion : System Reboot and Recalibration Required
  • Intermittent Data Errors, Data Contamination, or Data Loss : Process “Do Over” Required
  • Random Equipment Component Failure : Downtime Caused Process Backlog

When above are of significant magnitude and duration, these disturbances can cause malfunction of sensitive electronic equipment and damage to both components and insulation.

Solution for resolving the problem – The hospital laboratory mitigation solution included:

  • Replacing several line-interactive uninterruptible power supply units with true-online, double : conversion UPS units,
  • Installing high-quality transient voltage
  • Surge suppression device, equipped with very good filtering, on the branch circuit panel board supplying laboratory equipment
  • Upgrading branch circuit wiring

Conclusion: Application of the appropriate mitigation solution dramatically improved power quality, thereby completely eliminating or significantly reducing the adverse affects. The return-on-investment payback period for power quality improvements ranges from 1-3 years for most equipment and services.

CASE STUDY 2

Problem Statement: One of the multispecialty hospitals in Southern India was facing problem in their ultra sound machine. The hospital was not able to operate an ultra sound machine, as image on the monitor was blurred to an extent that it was not possible to use it for any kind of diagnostic assessment. From the detailed study of the system, it was found that; there was noise present in the supply which was travelling through the ground loop. Presence of this noise was generating disturbance on the monitor of the ultrasound machine. 
Problems faced by the hospital

  • Referring patients to other departments or outside hospital for various tests conducted by ultra sound machine.
  • Time delay for treatment.
  • Estimated loss in revenue was around Rs. 4-5lakhs per month.

Solution: It was proposed to the hospital management for installing isolation transformer as it breaks the DC connection between components while passing the differential signal on the line. Even if one or both components are ungrounded (floating), no noise was introduced.

Conclusion: Applying necessary mitigation techniques helped in improving PQ issue, thus completely eliminating the losses.

CONCLUSION

In the present scenario, power quality is not just about uninterrupted power but more importantly about supply of voltage and current at a constant rate i.e. sinusoidal waveform complying with defined standards. In today’s world of digital economy, even partial drop in voltage for even a moment cannot be tolerated as the electronic equipment used cannot resist even a fluctuation of the same, thus causing equipment to shutdown and remain so even after resumption of services. Investment in PQ is essential for all; as it can lead to equipment failing or their malfunction which can lead to quality and reliability issues. Avoiding premature equipment failure and improving equipment reliability – to minimize downtime and save money – should be the primary focus for facility managers. The addition of energy-efficient equipment is a bonus. PQ investments need to be perceived as an instrument of insurance against unforeseen life and economic loss due to poor PQ environment besides damage to the reputation and credibility of developer, builder or architect / consultant.It is all about doing right first time when you want to address PQ towards high PQ approach.

REFERENCES

  1. Electric Power Research Institute (EPRI) – Power Quality in Medium and Large Commercial Buildings
  2. United Nations Development Programme (UNDP) – Energy Efficiency improvements in Commercial Buildings
  3. S Khalid & Bharti Dwivedi – Power Quality Issues, Problems, Standards & their Effects in Industry with corrective means
  4. Manas Kundu, Asia Power Quality Initiative (APQI) – Poor Power Quality – Are Developing Economies at Risk?
  5. Case Study – Hospital Laboratory, USA Frost & Sullivan – Bright Green Buildings – Convergence of Green and Intelligent Buildings
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