|
|
| View previous topic :: View next topic |
| Author |
Message |
kashirachiam
Posts: 15
|
 Posted: Thu Mar 22, 2007 2:38 pm Post subject: Cooling Design Calculation |
 |
|
I'm trying to run the cooling design calculation for my model which is office building. The weather data is Malaysia which is summer all around year. The max temperature of the weather is about 35. My data shows me that the highest air temperature is about 45 celcius for the showroom in the ground floor. Is it reasonable? And if i model the building with air-cond off (switched off the cooling), what else setting i should do?
I attached the file.
Thanks.
Regards,
Kashirachiam
| Description: |
|
Download |
| Filename: |
aircond off.dsb |
| Filesize: |
726.47 KB |
| Downloaded: |
384 Time(s) |
|
|
| Back to top |
|
 |
Andy Tindale
Posts: 1234
Location: Stroud |
| Posted: Thu Mar 22, 2007 6:17 pm Post subject: |
|
|
Kashirachiam,
Your showroom zones have very high solar gains, medium lighting gains and relatively low levels of equipment gains. There is no cooling (neither natural ventilation nor active cooling) so naturally the space gets very hot in the afternoon.
You should try a combination of reducing the solar gains (solar shading devices, different glazing types), reducing lighting gains (energy-efficient lighting systems, lighting control etc) and of course you will need some cooling (natural ventilation, mechanical ventilation possibly with cooling coils).
Regards,
Andy
|
|
| Back to top |
|
|
kashirachiam
Posts: 15
|
| Posted: Fri Mar 23, 2007 4:23 pm Post subject: |
|
|
Dear Andy,
For the cooling design calculation data, I noticed that the heat gain of glazing of mezzanine floor is always -ve values. I thought the heat gain will be +ve value from the afternoon to the evening. But for GF, the heat gain of glazing behaves normal for me when it gains heat in the evening and release heat at night.
What makes -ve value to the mezzanine floor? Convective heat from zone to outside?
|
|
| Back to top |
|
|
Andy Tindale
Posts: 1234
Location: Stroud |
| Posted: Sun Mar 25, 2007 11:05 pm Post subject: |
|
|
Yes, when the zone is very hot heat conduction through the glazing will be from inside to outside, i.e. it is a heat loss. Note that 'Glazing heat gain' does not include solar radiation.
| Program documentation for 'Glazing heat gain' wrote: | Glazing heat gain - the total heat flow to the zone from the glazing, frame and divider of exterior glazing excluding transmitted short-wave solar radiation (which is accounted for in Transmitted solar gains below). For windows without an interior shading device this heat flow is equal to:
+ [Convective heat flow to the zone from the zone side of the glazing]
+ [Net IR heat flow to the zone from zone side of the glazing]
– [Short-wave radiation from zone transmitted back out the window]
+ [Conduction to zone from window frame and divider, if present]
Here, short-wave radiation is that from lights and diffuse interior solar radiation. |
Andy
|
|
| Back to top |
|
|
kashirachiam
Posts: 15
|
| Posted: Wed Mar 28, 2007 5:57 am Post subject: |
|
|
Dear Andy,
Thanks for ur replies which help me a lot in solving problems. From my results, double glazing shows higher heat gain as compared with single glazing. I had read through previous topic and i found that u had made explanation about the heat gain by glazing. But i still hv doubt about it. Double glazing reduces the inside temperature but why the heat gain for double glazing is higher? What assumption should i make?
One more thing, I'm using the version of 1.2.2.002. The simulation result of comfort data is not same with the cooling design. I got higher temperature in cooling design calculation but lower temperature in simulation. What makes this happen?
Thanks a lot.
Regards,
Kashirachiam
|
|
| Back to top |
|
|
Andy Tindale
Posts: 1234
Location: Stroud |
| Posted: Thu Mar 29, 2007 4:17 pm Post subject: |
|
|
| Quote: | | Double glazing reduces the inside temperature but why the heat gain for double glazing is higher? What assumption should i make? |
In a zone that is hotter than outside, the glazing will provide a conductive heat loss. The equivalent double glazing will give a smaller loss. I'm not sure about the inside pane temperature - this could be similar for single and double glazing depending on the nature of the window panes and the inside to outside temperature difference. The higher 'window gain' results for the double glazing seem reasonable to me.
| Quote: | | I got higher temperature in cooling design calculation but lower temperature in simulation. What makes this happen? |
Cooling design simulations use worst-case ASHRAE summer design outside conditions whereas simulation uses real measured hourly weather data which will generally be less extreme than the summer design weather data.
Regards,
Andy
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by p h p B B
|
|
Home
FAQ
Search
Log in to check your private messages
Usergroups
