Hi all,
I am preparing a small piece for my web site and thought that it could be interesting for the group. If you have any comments, let me now. Hakan Individual room temperature control in HVAC systems. by Hakan Falk, Energy Saving Now. Research at Royal Institute of Technology (KTH) about individual room temperature control shows some interesting and basic results. I would be very surprised if this kind of investigation has not been duplicated in many research institutions of the world. They are simple findings and give a very large potential for energy savings. The investigations concerns the coupling between two rooms of different temperatures and the exchange between them. It is only necessary to discuss one simple sample of the investigations, to exemplify our points. Between two rooms and with an open door as the connection, with individual AC units and temperature control in respective rooms. At 2.0 degree Celsius control difference between the rooms, the airflow between them was measured to be 50 cubic meter per hour (3 to 4 exchanges of air between them per hour). The obvious conclusion of this is that the AC units in the rooms had to heat 2 degrees Celsius in one and chill 2 degree Celsius in the other one, an extra volume of 50 cubic meter of air per hour. It is quite a substantial energy waste and energy cost, for the luxury of having a door open and individual room temperature control. The situation get even more complicated if we look at possible effects in the larger HVAC perspective and consider the ventilation with re-circulation of air. The possibilities of fast fixes and large energy savings could go along the following lines, - Secure that doors are not open to rooms with individual thermostats. The cheapest would be automatic door shutters and a policy against open doors. - Disabling of the local thermostat when the door is open and replacing it with the general temperature control. A simple electronic circuit with delay for allowing normal opening/closing of the door. - Do not use local room thermostats all together and only use central thermostats for one or more sections that are isolated and without the direct coupling like or similar to open doors. For individual cooling units in homes or small offices, with heating elements or reversible to heat pump. The above advises are very valid and the following can be added for substantial energy savings, - Never run the units in automatic mode, if you have more than one in the same space or in different spaces with open doors or equivalent coupling between the spaces. - If possible use drying mode instead of temperature mode for cooling. Humidity level is more important for cooling the human body, than air temperature. We often find it more comfortable and tolerate much higher temperatures, if the humidity level is below 60%, than if the humidity is high. An observation that almost all people recognize and agree with. The above is quite logical knowledge and must be in any HVAC engineers mind, it should also be dealt with in any energy audit of a building. The realities are however a different matter and it is surprising how often we find the situation described above. ********************************************** If you want to take a look on a project that is very close to my heart, go to: http://energysavingnow.com/ http://hakan.vitools.net/ My .Net Card http://hakan.vitools.org/ About me http://vitools.com/ My webmaster site http://playa.nu/ Our small rental activities ********************************************** "A truth's initial commotion is directly proportional to how deeply the lie was believed. It wasn't the world being round that agitated people, but that the world wasn't flat. When a well-packaged web of lies has been sold to the masses over generations, the truth will seem utterly preposterous and its speaker a raving lunatic." -- Dresden James "No flag is large enough to cover the shame of killing innocent people" -- Howard Zinn "Nobody grows old merely by living a number of years. We grow old by deserting our ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul." - Unknown Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
