Hello
Room Set Temp...Is it benificial
قبل حلول الصيف , تكثر الوصايا والارشادات حول ضرورة تقليل إستهلاك الطاقة من أجهزة التكييف وذلك لكي تقلل من الضغط على الشبكات الكهربائية حيث تكون الشبكة في أوج سعتها .
و من ضمن تلك الإرشادات : رفع ضبط درجة حرارة غرفة المعيشة الى 24 درجة مئوية , فهل هذه التوصية مناسبة للمستهلك العام ؟
Before summer , many recommend to set the room temp to a 24 C or even 25 C to avoid the unnecessarily power consumption during the peak summer when the power grid is already loaded .
Is the practice of increasing the Room Temp. Set Point a good choice ?
Here we try to answer the question by displaying of a mathematical modelling for a room and compare it set points at :
-20 C
-24 C
Before we answer the captioned question , let us explore few facts :
1-The public trend - Oversized air conditioners purchasing
This is driven by several factors :
- The unit selection method is not following properly engineered process
- The buyer wants to secure enough cooling at higher loads expected at extreme high summer temp.
- The buyer wants to be sure that the unit will not be short of capacity should he/she decided to set the room temp at low temp.
2-The Control of OFF/ON
The unitary air conditioners ( Window types , split units, package units..) usually equipped with the basic control of ON/OFF .
3-The ON/OFF system works on full capacity regardless of the heat load .
The On/OFF systems are a single speed system , therefore , whenever it works , it works 100% .
4-High Inrush Current
Whenever the system is started , the compressor draws high current , which is several times higher than the rated current .
This current which is at the start of each operation is called Inrush Current.
The High Inrush Current causes tear and wear to the compressor motor windings which raise maintenance issues and shorten the life cycle of the compressor
5-The Ideal Operation
The ideal operation is to keep the system run most of the time ; the more it is subject to ON/OFF cycles , the more it is subject to maintenance and shortened life cycle .
6-The Oversized systems suffer several ON/OFF cycles
The Oversized systems suffer continuous ON/OFF cycles even during the peak summer loads ; this is due to the fact the Oversized systems reaches the room temp. set point quicker than other systems which are sized as per the heat load ( Capacity = Heat Load at Peak Hours ) .
7-Conclusion : The Oversized systems + High Room Set Point Temp will result operation with several
So , setting the room to a high temp coupled with the oversized selection option will end up in frequent ON/OFF cycles .
The operation chart displays the room temp , the comparison between the expected operation of
- Oversized System which is in light blue , and
- Exactly sized system , which match the heat load of the room , which is dark blue )
The Oversized system is expected to operate under heavy ON/OFF cycles even during the peak summer hours ; and when the temp drops ( load drops) , the system suffer much more operational cycles.
Recommendation
So ,it is suggested that rather than just request the public to raise the Room Temp. Set Point , the following should be recommended :
1- Improve public awareness regarding the impacts of Oversized Units and the possible increase in maintenance and short life cycle .
2- Enforce the District Cooling Real Operational Data sharing . District Cooling emerged as a business since the year of 2000 ; the submeters ( Customer side meters , collects consumption data few times per an hour . District Cooling End Users Customers are in several thousands ; this lead to the fact that District Cooling Service Providers (DCSPs) have several billions of data points since the business started . These data if shared and published to the Public Domain , will for sure improve , not only the Public Awareness , but also it will provide the concerned authorities , the HVAC consultants ,..with the actual heat load per occupied space area ( BTU/Sq.ft ) . Such data could be sorted out and be classified to determine the heat load according to type of the building , level of green building implementation ,time of the year ,temp. set point,...
3-The data also should be incorporated into the formal energy related publications to reflect the exact consumptions of several types of aircon systems .
Currently , the publications published the expected power savings from particular systems , mainly the District Cooling (DC) ; however due to the fact the operational data of DC are dealt with extreme secrecy , the expected saving rather than the real are published .
The actual data , if shared and classified, will be of great benefit to the public, the HVAC industry(Consultants and Contractors and Products Manufacturers) , the concerned authorities,...
4-The concerned authorities should create the awareness of the limited benefits of the ON/OFF controls and investigate the possibilities of integrating the unitary systems with more advanced controls which math the output with the real heat load.
With all of these , the power consumption will be substantially reduced driven toward lower limits by a systematic approach and realistic figures.
The strategy to reduce the power consumption during peak hours should be a global rather than few recommendation being promoted without being assessed practica
