Question

A university campus has 200 classrooms and 400 faculty offices. The classrooms are equipped with 12 fluorescent tubes, each consuming \(110 \mathrm{W}\), including the electricity used by the ballasts. The faculty offices, on average, have half as many tubes. The campus is open 240 days a year. The classrooms and faculty offices are not occupied an average of \(4 \mathrm{h}\) a day, but the lights are kept on. If the unit cost of electricity is \(\$ 0.11 / \mathrm{kWh}\), determine how much the campus will save a year if the lights in the classrooms and faculty offices are turned off during unoccupied periods.

Short answer

Answer: $55,757.68

Step-by-step solution

1. Calculate the total power consumption of classrooms and faculty offices

First, let's find out the total power consumption of classrooms and faculty offices with the lights on. For classrooms: There are 200 classrooms, each with 12 fluorescent tubes consuming 110 W each. So, the total power consumption of classrooms is: 200 classrooms * 12 tubes * 110 W = 264,000 W (264 kW) For faculty offices: There are 400 faculty offices, each with half as many tubes as classrooms, which means 6 tubes per office. So, the total power consumption of faculty offices is: 400 offices * 6 tubes * 110 W = 264,000 W (264 kW) Now we add both values to find the total power consumption when all the lights are on. Total power consumption = 264 kW + 264 kW = 528 kW

2. Power consumption during unoccupied periods

The problem states that the classrooms and faculty offices are unoccupied for an average of 4 hours a day. We will first calculate the daily power consumption and then find the total power consumption for the whole year, 240 open days. Daily power consumption during unoccupied periods = 528 kW * 4 hours = 2112 kWh Now, let's calculate the total power consumption during unoccupied periods for the entire year. Annual power consumption during unoccupied periods = 2112 kWh/day * 240 days = 506,880 kWh

3. Calculate the cost savings

Now, we know the annual power consumption during unoccupied periods, and we're given the cost of electricity per kWh, which is $0.11/kWh. To find the cost savings, we will multiply this by the total unoccupied power consumption. Annual cost savings = 506,880 kWh * \(0.11/kWh = \)55,757.68 The campus will save $55,757.68 a year if the lights in the classrooms and faculty offices are turned off during unoccupied periods.

Key concepts

Power Consumption

Understanding power consumption in educational facilities starts with recognizing how energy is used in day-to-day operations. In our scenario, the focus is on the usage of fluorescent tubes in classrooms and faculty offices. Each fluorescent tube consumes power, measured in watts (W). To calculate the total power consumption, you need to multiply the wattage of a single tube by the number of tubes in use, and then by the number of rooms.

For example, the university campus in the exercise has 200 classrooms, each with 12 fluorescent tubes at 110 W each, leading to a considerable aggregate consumption. Additionally, power consumption isn't constant; it varies based on occupancy. When spaces are unoccupied, continuing to consume energy is wasteful. By identifying these periods and reducing consumption, significant energy savings can be achieved.

Electricity Cost Analysis

Breaking down electricity costs is crucial for financial planning in educational facilities. The cost of electricity is typically measured in kilowatt-hours (kWh), which represents the power usage over time. A kWh is equal to 1,000 watts being used for an hour. To analyze costs, follow these steps: first, figure out the total power consumption, as seen in the exercise example. Next, incorporate the cost of electricity per kWh, which is given as $0.11 in this case.

By multiplying the total annual power usage during unoccupied periods by the cost per kWh, you determine the potential savings through energy efficiency measures. This step of cost analysis helps institutions to budget effectively and invest in energy-saving initiatives.

Energy Efficiency in Education Facilities

Energy efficiency in education facilities is not just about saving money; it's also about reducing carbon footprints and promoting sustainable practices. Simple measures such as turning off lights during unoccupied times can have significant impacts. To implement energy efficiency, institutions should conduct regular audits, invest in energy-saving technologies like LED lighting, and encourage behavior changes amongst staff and students.

These strategies are part of a broader approach to create environments that are not only cost-effective but also environmentally responsible. For instance, intelligent lighting systems that automatically adjust to occupancy and natural light levels can further enhance energy savings. Energy efficiency in educational facilities is a practical demonstration of environmental stewardship to the community and provides a teaching moment for sustainability.