[BLDG-SIM] Thermal mass walls

Habaza11 at cs.com Habaza11 at cs.com
Wed Jun 25 10:24:14 PDT 2003


DOE also funded research on thermal mass which showed that thermal mass may have significant effect, minimal effect or adverse effect on cooling/heating  load. In theory, thermal mass in walls is like the balance wheel, which I don’t think will help in reducing the cooling load in the refrigerator  case. combining thermal mass with other factors such as infiltration, mechanical system sizing/operation, etc. may be!.
Hussein Abaza, Ph.D.
Assistant Professor
ECU.

Rick Strand <rkstrand at uiuc.edu> wrote:

>While this is a slight divergence from the original issue that Mark Case 
>brought up, I wanted to address one item in Christian Struck's 
>email.  Christian mentions a system of activating a thermal mass using a 
>passive nighttime conditioning scheme.  This could have wide applicability, 
>and it is partially the subject of a research paper on a "passive" radiant 
>ceiling slab system modeled in EnergyPlus that will be presented at the 
>upcoming ASHRAE meeting.  So, models for this idea already exist in 
>EnergyPlus and probably in other programs as well.  If you have an interest 
>in what EnergyPlus can do in this area, please let me know or come to the 
>presentation in Kansas City.
>
>Rick Strand
>
>At 03:58 PM 6/25/2003 +0100, Christian Struck wrote:
>>Nothing to rectify at all, but a small addendum.
>>A large thermal mass causes the heat transfer to slow down due to its
>>thermal resistivity. Nevertheless, if you have constant conditions of either
>>side of the wall you will still have a steady heat transfer. The temperature
>>difference between inside and outside (wind not taken into account) governs
>>the exchange. By comparing a wall with no thermal mass to a wall with large
>>thermal mass in equilibrium you will find the same rate of heat transferred.
>>Thermal mass is only beneficial to the internal climate under varying
>>internal and external conditions due to the storage capacity (time lag) of
>>the building fabric.
>>
>>Interestingly that the point, the industry started thinking about,
>>activating the thermal mass of buildings further by embedding water powered
>>pipework into the neutral axis of ceiling slabs or walls. That allows coolth
>>to be stored at night by running i.e. a water to air heat exchanger to be
>>available for passive conditioning during the summer day. Same principle
>>applies for heating.
>>
>>The principle is dead simple, but its benefits difficult to assess. Here we
>>go again, its our game, building simulation in order to assess the systems
>>energetic benefits.
>>
>>Check the link to Tarmac for Thermocast. (http://www.tarmacprecast.co.uk/)
>>
>>Christian
>>
>>
>>
>> > -----Original Message-----
>> > From: Callan, David [SMTP:dcallan at syska.com]
>> > Sent: 25 June 2003 15:16
>> > To:   BLDG-SIM at GARD.COM
>> > Subject:      [BLDG-SIM] Thermal mass walls
>> >
>> > I agree.  I assuming that the refrigerator is inside a larger facility
>> > shaded from the sun.  My understanding of thermal mass leads me to believe
>> > that it will have little effect on this refrigeration process.   Thermal
>> > mass plays a part when the loads change with time.  The thermal mass
>> > stores
>> > the heat to be radiated later.  This is obviously advantageous for
>> > building
>> > design in hot climates because the instantaneous solar load effect can be
>> > delayed to a time when the conduction load due to temperatures decreases.
>> > Hence reducing the peak sensible load slightly.  In the refrigeration
>> > process, the loads are more or less constant and direct solar would not be
>> > an issue.
>> >
>> > If anyone can elaborate on, or correct my explanation, I would appreciate
>> > it.
>> >
>> > David P. Callan, MS, PE, CEM
>> > Syska Hennessy Group, Inc.
>> >
>> > -----Original Message-----
>> > From: Habaza11 at cs.com [mailto:Habaza11 at cs.com]
>> > Sent: Wednesday, June 25, 2003 9:41 AM
>> > To: BLDG-SIM at GARD.COM
>> > Subject: [BLDG-SIM] Thermal mass walls
>> >
>> > Yes, I am with eQuest results and your guts!. DOE also funded research on
>> > thermal mass which showed that thermal mass may have significant effect,
>> > minimal effect or adverse effect on cooling/heating  load. In theory,
>> > thermal mass in walls is like the balance wheel, which I don't think will
>> > help in reducing the cooling load in your case. Other factors such as
>> > infiltration, mechanical system sizing/operation, etc. may be!.
>> > Hussein Abaza, Ph.D.
>> > Assistant Professor
>> > ECU.
>> >
>> >
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