Understanding Cooling Systems

We all use air conditioners to cool our homes and facilities. We need air conditioners to remain productive, since our body needs a cooler environment.

Human bodies burn calories through activity and due to this activity our body produces heat. The heat produced by our body makes it necessary to cool its own, otherwise, it overheats. For the body to be cooled, we have to follow the basic law of heat transfer, which is. heat transfers to a cold place, until a unified temperature is achieved.

But keeping a facility too cold produces another problem. too much cold and the body uses more energy to heat itself up. This is done through movements such as shivering.

Given the above, it was discovered that while everyone has their own healthy or optimal room temperature, the average comfortable temperature is between 24 to 26 degrees celcius.

So, we now know that we need a comfortable room to keep our bodies healthy and productive, and that magic number is 26 degrees celcius. But, how much air conditioner do I need?

For this, we need to get the room dimensions. Take the height, length, and width of a room. We can start off with an example that a room may have a 10 foot ceiling, have an 15 foot length, and 15 foot width. The total room size is 2250 cubic feet.

1 British Thermal Unit (BTU) can raise 55 cubic meters of space by 1 degree farenheit. If the room is 2250 cubic feet, raising it by 1 degree farenheit will require 40 BTU. We will need this to establish how hot is the room before cooling. If the outside temperature is 32 degrees celcius, and we want to bring it to 26 degrees celcius, 6 degrees celcius is equivalent to 42.8 degrees farenheit  (F=(C*1.8)+32)

42.8 degrees farenheit multiplied by 40 gives us 1,712 BTU to cool a room from scratch. If the room insulation is good against outside temperature, then there should be minimal effort by the air conditioner to keep the room cool against outside temperature.

We have to remember that while our house might have good walls and everything, any heat leak will bring in heat to the house, and that insulations merely delay heat transfer, not stop heat transfer. Case in point, it takes a long time to heat a brick to boiling hot compared to metal, but you will still be able to heat a brick. Windows are one of the poorest barriers of heat, and dark exterior colors help bricks absorb more heat.

Let us now take in how much heat each person produces.
A sleeping person produces around 250 BTU/hr or 75 watts
A sedentary but awake person produces around 400 BTU/hr or 120 watts
A person doing light work produces around 650 BTU/hr or 190 watts
A person doing heavy work produces around 2400 BTU/hr or 700 watts

We have to determine what are the activities that will transpire in the room. Is it a bedroom? A gym? An office?

For the sake of this example, let's take that the room is an office, with light work, and has 3 people who each produces 650 BTU/hr. This equates to 1,950 BTU/hr

Let us now take electricity. Every watt of energy used would create 3.412 BTU of heat A room with computers, light, and other appliances, produces a lot of heat accordingly. 5 40 watt bulbs and 2 180 watt computers will produce 1,911 BTU per hour.

Total BTU/hr produced by electric appliances and human activity equates to 3,861 BTU

The total starting BTU for a well insulated room is 5,563 BTU/hr or 92 BTU/min, but a room does not necessarily need to cool itself instantly. Therefore, we can take the 92 BTU/min requirement.

The initial room cooling startup will be around 1.8 kwh of electricity. After that, the required BTU will substantially decrease due to good room insulation.

Each horsepower is 745 watts. You may not need a large air conditioner to cool a room, since it is the initial shift of temperature is the primary concern. It would be best that the usual need + 50% would be considered, but then again, it is all dependent on design and strategy for implementing the room cooling system.

The value of good insulation is hopefully established by this literature, and as discussed, keep the room temperature at 26 degrees and help save the planet. Each degree can mean a lot in terms of electricity and carbon emissions

5 Essential Tips on How not to Waste Energy

While we have been promoting positive affirmations on the importance of going green, we have realized that there is an importance on the do nots as well. Here is a brief run down of how not to waste energy.

1. Do not keep non-essential appliances on standby - Conservation energy rules dictates that appliances that have a standby function do take a lot of electricity (especially appliances made at least 5 years ago). Do not leave appliances on standby when not in use and enjoy the savings later.

2. Do not be left unaware of your energy consumption - people who do not use energy meters end up on the losing end as people who do not monitor their own energy tend to consume up to 20% more energy than the rest. Get an energy meter and manage your energy consumption.

3. Do not keep old Air conditioners - It might have been a gift, but if it is more than 10 years old, a new airconditioner will pay itself off in less than a year.

4. Do not use incandescents - CFL have become so cheap that using incandescents is illogical. switch to energy efficient lighting and save that money that can go to a new shirt.

5. Do not leave water dispensers plugged overnight - Water dispensers can consume up to 400 watts per hour. When not needed, might as well keep it unplugged. Better yet, get a regular water dispenser and keep water bottles in refs.