Window AC UnitWindow Air Conditioning Unit is a small scale, primary/secondary system that used for providing both cooling and heating. Most conventional window units use evaporator and compressor to directly generate cooled air, while utilize electricity to provide heating. In some occasion, water is chilled or heated in order to stably control the room temperature. However, chilled water units are more costly than direct air cooling units.
For emergency shelter, window AC unit is a great potential choice since it is easy to install and uninstall from the structure. It is much more cost effective comparing with large scale, integrated system such as CAV or VAV. The limitation of window AC unit is, it is not efficient when used on building with large room area. And if multiple window units are installed, the overall operating cost is relatively expensive than CAV and VAV. Last but not least problem is, exhausting devices must be installed on the outer envelope of the structure, which may cause potential aesthetic issues. |
FanIt is hard to argue whether fan is a primary or secondary HVAC system because fan only affects the perceived air temperature on human body. It is notable that fan does not change the actual air temperature, thence it usually integrated with other HVAC systems. When fan is operated, air temperature on the one side orthogonal to the blade surface would be considered 'cooled', while air on the other side would be 'heated'.
There are two types of fans: 1. Installed fan that usually fixed on either ceiling or wall surface. 2. Portable fan which is easy to carry. For emergency shelter, both fans are favorable due to their advantage in terms of ease of assembly. The limitation of fan is, its ineffectiveness at extreme temperature. When room temperature is either too high or too low, fan can only be utilized as air distribution system. Hence, it must be combined with other HVAC systems such as window AC unit or heat pump to consistently control the room temperature. |
WindowWindow use isotropic materials, mainly glass to insulate the air circulation between two sides. window is considered as neither primary or secondary system. When it is opened, the air temperature inside the building would be consistent with outer environmental temperature. When it is closed, the room temperature would relatively isolated from outside.
Advantage of window is that it is easy to assemble and use, and does not require any operating cost. The image on right hand side shows a window installed on an emergency shelter. Since window does not artificially alter the air temperature, other HVAC system must be utilized simultaneously at extreme temperature. |
cav and vavConstant Air Volume(CAV) is a modern, integrated system that utilized for providing both heating and cooling at constant air flow. CAV constantly supply air into room at stable flow and temperature. It is considered both primary and secondary system. CAV is usually used for large interior space such as theaters, warehouses, and auditoriums.
Variable Air Volume(VAV) is considered as improvement of CAV. VAV provides air at variable flow and temperature. When using VAV system, the room temperature is monitored and controlled at certain temperature. For emergency shelter, both CAV and VAV are acceptable but also questionable. These two system are effective and efficient in terms of providing heating and cooling. There are also relatively easy to be installed. The limitation is the cost. Most emergency shelter are small in scale, while CAV and VAV are intended to be used for large building. |
convective heatingConvective heating is also a system that dedicated in providing heating. It is a primary system that heating is generated by heat pump than conveyed through convector or radiator. It is a closed system that air adjacent to the convector is heated then circulated inside the room.
Comparing with space heater, convective heating has better performance when the building size is large. For small sized emergency shelter, convective heating is more costly than space heater. |
SPACE heaterSpace heater is a group of heating system that dedicated into heating. Contemporary space heaters utilize electricity as the source of heating. The heat is conveyed into room by either water or fan. Space heater is a primary/secondary system.
For emergency shelter, space heater is favorable since most space heaters are small scaled, which means they are easy to carry and install. Comparing with integrated system such CAV and VAV, space heater is more cost effective. The limitation is that space heater only generate heat, thence other system must be used when cooling is required. |