"So, you study air conditioning?"

After scanning through previous blog posts I have realized that many times I promised a post which gives an overview of what my Fulbright research project actually entails. (ie: where your tax dollars are actually being spent to support my conquest for cultural mutual understanding between Singapore and the USA). Therefore I'd like to give a brief, yet enthralling explanation of what I'm doing here and where I'm at so far. Disclaimer: "enthralling" used with sarcasm.

In a nutshell, the main goal of my project is to further develop a new type of air conditioning system which has the potential to more efficiently use cooling energy in buildings and increase the thermal comfort and indoor air quality for the occupants. How? Well, let me explain

I don't think this is news to anyone- Singapore is HOT and HUMID. Air conditioning systems are designed with two main functions: to cool the air (known as the sensible cooling load) and remove moisture (the latent load). Most systems in the world do this by cooling the air down to a certain point (around 55 deg F/12 deg C) and then supplying it to all of the spaces at whatever flow rate is requested by the thermostat. Sounds simple right? Well the complicated part is when the system has to supply a certain quantity of "fresh" air from the outdoors in addition to the recirculated air from the space. In potentially densely populated zones such as classrooms and movie theaters, this amount of fresh air could be very high - sometimes more than what the thermostat is asking for. This situation is what we is referred to here as "Singapore Winter". The system is required to supply more cold air to the space to accommodate the fresh air requirement than what is needed to cool the space.  Since the fresh air and recirculated air are mixed before cooling and only a small percentage of the supplied air is from the outdoors, a significant supply of frigid air is dumped into the space resulting in a refrigerated case-type feeling when the space is not a max capacity.

In many cases in the US, the way this situation is mitigated is by having a reheat coil in the duct serving each room which can reheat the air back up so the occupants don't get too cold. Common sense tells us that this is silly - cooling air down and reheating it back up in the middle of the summer. Many energy codes, including Singapore, restrict or ban such reheat systems as they are wasteful.

In an attempt to solve both the cooling and dehumidifying problem in an energy efficient way, a group of professors here have developed and tested a new way of orienting a typical A/C configuration so that the fresh air and recirculated air are not mixed and are controlled separately. Without going too far into the details, this system, called the Single-Coil, Twin-Fan System (SCTF) saves energy by allowing the fans to decrease speed in response to both thermal and humidity related loads which translates into fan and cooling energy reductions. A very good, albeit lengthy, animated presentation can be found on the website of a spin off company which the professors created (and I guess I'm sort of working for).

My task in all of this is to modify or create modules within the building energy simulation program EnergyPlus which would allow it to simulate and predict the energy consumption of this unique system type. This would allow engineers to test this system in theory and compare it to conventional system types in various climates and building types. All-in-all it could help reduce some of the 700,000,000,000 kWh used in buildings per year (40% of all energy consumption), create more awareness of poor conventional A/C practices, and promote communication between Singapore and other places with similar climates (many located in the USA)

Those of you with technical interest, (and who knows, maybe even feedback!!): below is a graphic with my major tasks outlined on a schematic of the SCTF system.