Engineering Board Exam Reviewer · Environmental Engineering · medium
A building replaces 100 lamps of 40 W with 10 W LEDs. The lamps operate 10 hours a day, every day. How much energy is saved per year?
- 14,600 kWh
- 10,950 kWh
- 1,095 kWh
- 10,950,000 kWh
Answer
B. 10,950 kWh
Solution
Savings = 100 × 30 W × 10 h × 365 d = 10,950,000 Wh = 10,950 kWh ( 7,665 kg CO2 at 0.7 kg/kWh).
More Environmental Engineering questions
- A compost mixture contains 40 kg of carbon and 1.6 kg of nitrogen. What is its C/N ratio?
- A 100 m3 room is supplied with 500 m3/h of fresh air. How many air changes per hour (ACH) does it receive?
- A gas concentration of 10,000 ppm by volume is equivalent to:
- A water treatment plant has a capacity of 2 million liters per day (MLD). What is this in m3/s?
- For dilute aqueous solutions, a concentration of 1 mg/L is approximately equal to:
- A treatment plant receives 5000 m3/day of wastewater with a BOD of 200 mg/L. What is the BOD mass loading?
- A community uses 200 L per capita per day of water, and 80% of it becomes sewage. What is the per capita sewage flow?
- A septic tank with a liquid volume of 4.5 m3 receives 1.5 m3 of sewage per day. What is its detention time?
- Radon, a naturally occurring indoor air pollutant, is a:
- The main cause of 'sick building syndrome' is usually: