southern california research initiative for solar energy ... energy consumption.pdf · southern...

Southern California Research Initiative for Solar Energy (SC-RISE)

Sasan [email protected]

Mentor: Dr. Sadrul [email protected] Photo Courtesy: Engineering

Building IIUniversity of California, Riverside

www.cert.ucr.edu www.scrise.ucr.edu

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Heating, Ventilation and Air Conditioning (HVAC)

Energy Consumption &

Electrical Analysis for large Commercial and Industrial Buildings


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Outline of presentation• Introduction• Basic of Air – Conditioning process• HVAC: Cooling and Heating Load Estimation

• Cooling/Heating Load Components• HVAC Load Design and Analysis Software• Electrical Demand and Demand Charges• Suggested HVAC Design Improvements• Conclusion• Reference

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Heating, Ventilation and Air Conditioning (HVAC) is a vast field.

The basic purpose a of Heating, Ventilation, and Air Conditioning (HVAC) system is to provide interior thermal conditions that a majority of occupants will find appropriate and comfortable.

Depending on the complexity of the requirements, the HVAC designer must consider many more issues than simply keeping temperatures comfortable.

HVAC systems include a range from simple systems used for heating or cooling such as a hand-stocked stove to the extremely reliable air conditioning systems found in sub marines.

Energy efficient equipment are need of the industry.Global awareness towards energy saving is reflected in HVAC industry.

Introduction


There are seven main processes required to achieve full air conditioning:heating, cooling, humidifying, dehumidifying, cleaning, ventilating, and airmovement. The requirements and importance of the seven processes varywith the climate.

Scope of Modern HVAC:

Some of the areas of research, regulation, and responsibility include indoorair quality, greenhouse gas emissions, and energy conservation.

This research has focused on finding methods as how to conserve energyuse by HVAC units and suggesting alternative solutions.

Basic of the Air – Conditioning process

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Basic HVAC system air circulation

Figure. Basic HVAC system air circulation

A typical HVAC system is comprised of the following component:

• Chilled beam• Circulator

pump• Cooling tower• Damper• Diffuser• Duct• Economizer• Fan coil unit

• Fan (mechanical)• Heater• Heat exchanger• Humidifier• HVAC control

system• Piping• Valve


HVAC: Cooling and Heating Load EstimationHeating and air conditioning systems use the principles of heat transfer to maintain comfortable indoor conditions for people.

Principles of Heat Transfer• Heat energy cannot be destroyed; it

can only be transferred to anothersubstance.

• Heat energy naturally flows from ahigher-temperature substance to alower-temperature substance, inother words, from hot to cold.

• Heat energy is transferred from onesubstance to another by one of threebasic processes: conduction,convection, or radiation.

Methods of Heat Transfer

Conduction is the process oftransferring heat through a solid.Convection is the process of transferringheat as the result of the movement of afluid.Radiation is the process of transferringheat by means of electromagnetic waves,emitted due to the temperaturedifference between two objects.


Conduction heat gain from outdoors through the roof, exterior walls, skylights, and windows.

Conduction heat gain from adjoining spaces through ceiling, interior walls and floor.

Cooling/Heating Load Components

• Internal heat gains due to people, lights, appliances, and equipment in the space.

• Heat gain due to hot, humid air infiltrating into the space from outdoors through doors, windows, and small cracks in the building envelope.

• Solar radiation heat gain through skylights and windows.

The space cooling/heating load is the rate at which heat must be removed/added from/into a space in order to maintain the desired conditions in the space.

The cooling/heating load for a space can be made up of many components:

Photo Courtesy: American Standard Inc. 2000


Many computerized load analysis programs arecommercially available to make thesecalculations quick and simple, eliminating theneed for tedious hand calculations andnumerous iterations.

TRACE 700The TRACE Load 700 program is acommercial Heating, Ventilation and AirConditioning software platform developed byTrane’s CDS Group. TRACE 700 calculationsapply techniques recommended by theAmerican Society of Heating, Refrigerating,and Air-Conditioning Engineers (ASHRAE).

HVAC Load Design and Analysis Software

Photo Courtesy: Trane Company Inc.

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Residential and commercial buildings account for a large portion of U.S. energy consumption.

Using commercially available and cost-effective advanced technologies, building energy consumption could be reduced.

More people, more households, and more offices, increase service demand, more air conditioning, more computers, etc. resulted in the fact that energy use in buildings has grown compared to the past.

However, the application of modern technology, improved appliances, more energy efficient buildings, and better building designs could lower energy consumption for both residential and commercial type of buildings.

If we assume that all these energy efficient technologies could be implemented, then we could claim that in future building energy use could be reduced which could correspond to annual energy savings.

Electrical Demand and Demand Charges

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Continued: Electrical Demand and Demand Charges

Electric demand refers to the maximum amount of electrical energy that isbeing consumed at a given time.

Electrical Utilities typically charge commercial and industrial customers forboth consumption (kWh) and Demand (kW or kVa).

• Electric rates vary by state and utility company.• Utilities have different tariffs for different types of users. Larger users

tend to get more favorable rates than small users.• Some utilities offer different rate periods based on time of day or

calendar periods.

The electric utility uses demand meters that measure flowing electricity.Demand meters register the highest rate of electrical flow (or current) duringa billing period; the meter records an average flow for every 15 minuteinterval. The customer is billed for the highest average 15 minute flowduring the billing period.

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Figure: RPU System Peak Demand Day, System Total Megawatts

• Battery charging Off Peak: 1 – 7 a.m., Energy delivery On Peak: 1 – 7 p.m.• Shift some building activities from On-peak to Off-peak.• Use batteries to store the electrical energy and use this energy during day peak

time.

Continued …

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With previous slide explanation of the electrical demand and demand charges, now let’s look at the electrical charges for the following location:

Quakes Stadium, Rochester Ave, Rancho Cucamonga, California

The total billing amount, especially the demand charges, for the four months, June – September were among the highest months.

Figure 1. Total billing Amount for “8408 Rochester Ave” location

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As we can see by shifting the demand charges from On-peak to Off-peaktime, the charges would be dramatically lowered.

Break Down of the electrical charges:

Figure 2. Electrical/Demand Charges for a period of one year for a 8408 Rochester Ave. location


Suggestions ???

So, keeping in mind that HVAC systems consume a large portion of energy

consumptions by buildings, what factor are influential for a HVAC designer

designing the HVAC system that can subsequently yield saving a lot of money?


Reference

2001 ASHRAE Handbook of Fundamentals

ASHRAE. 1998: Fundamentals of heating and Cooling Loads. Atlanta: American Society of Heating, Refrigerating And Air-Conditioning Engineers, Inc.

Trane C.D.S. Program Description and Capabilities. Cooling and Heating Load Calculation Principles, ASHRAE Psychrometry Air Conditioning Clinic (Trane literature order number TRG-TRC001-EN)

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