A three phase, 380-volt system, has the following voltage measurements: Va = 375 volts Vb = 380 volts Vc = 391 volts Calculate the percent voltage imbalance.

A. 1.1%

B. 2.4%

C. 3.4%

D. 5.5%

E. 6.2%

If the temperature difference across an external wall is 20°C and the heat flow across the wall is 2.5 Watts/m², calculate the insulation value of the wall (including inside and outside air films)?

A. R = 4 m²-°C/W

B. R = 6 m²-°C/W

C. R = 8 m²-°C/W

D. R = 10 m²-°C/W

E. R = 12 m²-°C/W

A concentrating solar thermal system collects 5 GJ/h of thermal heat, which is delivered to a 94% efficient hot water generator. The hot water generator is used to raise the water temperature from 15°C to 65°C. The specific heat of water (Cp) is 4.2 kJ/kg-°C. What flow rate (liter/second) of hot water can be delivered from the hot water generator?

A. 4.2 liter/second

B. 6.2 liter/second

C. 9.2 liter/second

D. 12.0 liter/second

In a typical compressed air system, energy can be saved by which of the following actions?

A. Reducing the capacity of the compressed air receiver tanks

B. Reducing the air distribution pipe size

C. Raising the air pressure

D. Decreasing supply air pressure

E. Move the inlet air filter to a warmer location

A new lighting system costs $60,000. The new lighting system has a 15-year life and the minimum required rate of return (MARR) is 15%. How much must the new lighting system save to be life-cycle cost effective?

A. $10,260/year

B. $12,556/year

C. $15,650/year

D. $27,090/year

E. $33,200/year

A cooling tower is delivering water to a chilled-water plant. The cooling tower outlet temperature has a 6°C approach temperature to the ambient air, wet-bulb temperature. The outside air conditions are 20°C dry bulb, 60% relative humidity. Using the psychrometric chart, at what temperature can the cooling tower deliver water to the chilledwater plant?

A. 13°C

B. 17°C

C. 21°C

D. 25°C

When should commissioning be included in the design and construction of a facility?

A. When the planning process begins

B. When the design is finalized

C. When installation of the energy systems begins

D. When construction is finalized

E. When the occupancy permit is accepted

Using a degree-day base of 18°C, calculate the number of cooling degree days (CDD) if the outside temperature is a uniform 25°C throughout the year (365 days/year).

A. 1,845 CDD/yr

B. 1,955 CDD/yr

C. 2,250 CDD/yr

D. 2,555 CDD/yr

E. 2,975 CDD/yr

A facility uses 250,000 kWh in a 31-day billing period. The peak demand in the billing period is 1,200 kW. What is the facility partial load factor?

A. 28%

B. 33%

C. 45%

D. 66%

E. 77%

An air-conditioning unit delivers 10,000 kJ/h (thermal cooling). The equipment uses singlephase electrical power at 220-volt and 5.25 amps with a power factor of 100%. Calculate the coefficient of performance (COP).

A. 2.4

B. 3.2

C. 6.2

D. 13.2

E. 16.1

A 7 bar (gauge pressure) compressed air system has 5 leaks that are 3 mm in diameter and 3 leaks that are 6 mm in diameter. The compressed-air system is pressurized 8,760 hours per year. Electricity cost is $0.10/kWh. What is the annual cost of the leaks in the compressed air system?

A. $18,150/yr

B. $25,220/yr

C. $30,910/yr

D. $48,480/yr

E. $56,500/yr

At the end of a performance contract, who owns the equipment installed by the project

A. The bank

B. The energy service company

C. The equipment manufacturer

D. The company that paid the contract payments