ACMV-Air Conditioning & Mechanical Ventilation

What is ACMV?

Basically we all know it as air conditioner, which provides environment comfort to our living space. I won't go too detail with how the ACMV works as this will take as much as 30+ pages to explain it (scientifically & technically). All you need to know is that to have the cooler air supplied to our rooms or areas, the ACMV will need to make heat transfer. To do that, they will need refrigerants that transfer the heat. The warm air is passed over an evaporator coil (or known generally as cold coil) with the refrigerant and the heat flows from the warmer temperature to the cooler temperature. Thus, the flows of the heat is called heat transfer.

Picture from http://climatecontrolhickory.com/wp-content/uploads/2013/08/air-conditioner-5.jpg

Types of Refrigerant

What is a refrigerant? Well imagine that you want to cool your drinks, you need ice cube. So refrigerant is like ice cube but it's in a liquid & gaseous form. It's a substance or mixture whereby it undergoes phase transitions from a liquid to a gas and back again. There are two types of refrigerants which are R-22 and R-410A. The R-22 is an old standard which is a hydrochlorofluorocarbon (HCFC) compound that contains ozone-depleting chlorine. It is slowly being phased out as this is not an environmental friendly material. So now we shall use R-410A which doesn't contain chlorine and considered as ozone-friendly.

What is SEER & EER?

Seasonal Energy Efficiency Ratio, also known as SEER, measures the air-conditioning cooling efficiency. The SEER is the ratio of cooling in BTU (British Thermal Unit) to the energy used in watt-hours. The higher the SEER, the better the efficiency in cooling.

On the other hand, EER, which is Energy Efficient Ratio, is the ratio of output cooling energy in BTU to input electrical energy in watt-hour. But the difference with SEER is that the operating period. SEER measures throughout the whole year (which includes the 4-seasons for some countries) whereas EER measures during a single point of environment. The higher the EER, the better the cooling efficiency of the device.

So how do we know when to use SEER or EER?

SEER can be used to compare one air-conditioning unit to another directly. However, it should not be used to measure how efficiently your new air conditioner will operate or how much money you can expect to save without making a calculation.  This is because as discussed above, a SEER rating is only a rating based on a standard test across a specific seasonal temperature range.  As such, use the calculation in the SEER section above to first figure out what your equivalent SEER rating would be for your climate zone, then make the best decision for your area.

EER ratings are more commonly encountered with smaller window-mounted air conditioners.  An air conditioner’s EER rating is best used to objectively compare air conditioners or to do any type of load or engineering calculation.

How to choose an energy efficient air-conditioning

Much like automobile manufacturers, today’s air conditioner manufacturers are required by law to evaluate and rate their equipment according to its energy efficiency. This rating is known in the industry as an Energy Star. The higher numbers of star in the label, the better SEER rating and higher efficiency for the air-conditioning.

Based on Electricity Regulation 1994 (Amendments 2013) Regulation 101A (3) 
"Any equipment that meets all the requirements of efficient use of electricity under subregulation (1) shall be affixed with an efficiency rating label in such form and manner as may be determined by the Energy Commission."

Most new homes with central air-conditioning come equipped with a standard builder’s model. However, when replacement becomes necessary, property owners can upgrade their air conditioning by specifying a more energy-efficient system.

The Rheem Prestige Series™ High Efficiency model, for example, has a SEER of 18.00, among the highest available. It’s significantly higher than today’s standard models, many of which carry SEER’s of at least 13.

High SEER models are generally more expensive, but can easily make up the difference by reducing your home energy bills over the long run. There are so many types of air-conditioning and it's up to you to decide which type that is suitable for the area that needs to be cooled.

Impact to the environment

So we have talked about high efficiency air-conditioning since the beginning but what is the reason that I'm so emphasized on using this costly equipment, compared to those conventional air-conditioning without Energy Star?

Energy Use - The electricity generated to power air conditioning carries both global and personal health consequences by burning fossil fuels such as coal. These power plants discharge clouds of soot and other pollutants into the atmosphere. Among these are mercury and carbon dioxide (CO2).

HCFC - As I mentioned in the "Types of Refrigerant", the cooling agents which are the ozone-depleting hydrochlorofluorocarbons (HCFCs), had depleted 95 percent less ozone. However, booming demand for air conditioners in hot climates such as India and China has upped the chemical's output in developing countries 20 to 35 percent each year, causing damage at an alarming rate and possibly setting back ozone recovery by 25 years.

Personal Health -  Dirty filters can allow allergens, pesticides and other particulate matter to enter your home from the outside, posing threats to indoor air quality. Exposure to those pollutants can trigger a host of health problems, including allergies and asthma and eye, nose and throat irritation.

So the question is, do we really need air-conditioning?

Well, this is a very subjective question. It's all based on the individual's needs. We can either use the active way (using the air-conditioning to cool down the air) or we can use the passive way (building the house facing the north or east). There's been many standards that are available to us (LEED, GBI, Passivhaus) for building an energy efficient house, but I'll go deeper on those topics in my next blog.

Hope you enjoy reading this info.

See you again next time.