Lesson Plan - Get It!
HVAC engineers specialize in keeping buildings like your home or school the right temperature -- not too hot, not too cold.
In order to do this, they can design and install an air conditioning system to keep a building cool or add improved insulation to keep the heat in.
In fact, that's what the "H" and the "AC" stand for -- heating and air conditioning.
The "V" is short for ventilation, which means moving air where you want it to go -- another way we can make a building more comfortable.
Heating, Ventilation, and Air Conditioning
For more information on what HVAC entails, watch HVAC Training - Basics of HVAC from Price Industries:
In order to become an HVAC engineer, you will most likely need to earn a bachelor's degree in either HVAC engineering technology or mechanical engineering.
You will also probably want to take graduate-level courses in order to have better career prospects.
The Bureau of Labor Statistics (BLS) predicts that HVAC techs will be added at a rate of 15 percent through 2026, a rate that is more than twice as fast as most other occupations.
- So, what exactly does an HVAC engineer do?
Most HVAC engineers go from project to project, working at each one for as long as necessary.
When an HVAC engineer starts a project, their first step is to survey the building they will be working on. When you survey something, you look at it very carefully and thoroughly.
They might walk through the site while carefully taking notes on their observations such as:
- How big are the rooms, the halls, the windows?
- What are the roof and floors like?
- On average, how many people are in the building?
They also need to know how the building is used and what the outside climate is like. As you can probably imagine, it's a lot more difficult to be an HVAC engineer in an area with extreme weather differences than someplace where the climate is more moderate.
Convection is an important concept that HVAC engineers use often.
To understand convection, you must first understand density. Density describes how tightly packed, or squished, the molecules of an object are.
Cold air is denser because the molecules are more tightly packed together, and hot air is less dense because the molecules are spread out and have more "empty space" around them.
This difference in density causes the air to move. The denser, cold air sinks while the less dense, hot air rises. This cycle is called a convection current. Convection is one way that thermal energy can be transferred.
Let's imagine that you are an HVAC engineer, and your newest project is a large library.
One of the library's main issues is that heating costs were abnormally high last winter.
Each room in the library has its own radiator that fills with hot water to allow the heat to radiate into and warm the library. Radiate means to move through empty space. Thermal radiation is a type of heat transfer.
(For more information on this, check out our lesson found under the Additional Resources in the right-hand sidebar.)
The radiators in the library appear to be working fine. However, the heat is not staying in the rooms and seems to be "escaping" somehow. The thermostat is registering that the rooms are cold and is, therefore, running the heat continuously all day.
A thermostat senses the temperature of an area, and then performs actions to adjust the temperature accordingly.
For example, let's assume your thermostat is set at 72 degrees. If the temperature dips lower than 72, the heat will turn on. When the temperature is comfortably above 72 degrees, the thermostat will turn the heat off.
Unfortunately, the heat from these radiators also traveled via conduction to the metal window sills and made them painfully hot to touch. This is not only bad for the library's budget, but the extra energy used also has a negative effect on the environment.
- The question is, where could the heat be "escaping"?
Your knowledge of convection tells you that hot air rises, so it would be a good idea to inspect the roof. Aha! You found that the roof is very worn in parts and doesn't have enough insulation. Insulation means to stop heat from entering or leaving.
In this case, insulation refers to the fuzzy or foamy stuff builders put in walls to prevent the loss of heat.
Cooling the library during the warmer summer months is another issue. The library does not have the budget to install centralized air conditioning, so window air conditioners had been purchased and added to each room. Unfortunately, they didn't seem to be working very well despite only being a year old.
When you completed your survey of the library, you saw that the air conditioners were placed in the bottom window in each room -- only a few inches off the floor.
- Why do you think the air conditioners aren't cooling the room effectively?
- How can we fix the issue without purchasing all new air conditioners?
Hint: think about how we can make convection do some of the work for us.
- Did you figure out that the issue wasn't the air conditioners -- it was their location?
If the air conditioners were moved to a higher location in each room, then the cool air would sink down onto the people instead of staying near the floor.
The librarian will be very happy to hear that he doesn't have to purchase new ACs, which would have cost the library a lot of money.