Diurnal Temperature Range

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Author Message Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 593 Registered: 10-2003 Posted on Thursday, March 25, 2021 - 12:01 pm:    DTR is the spread between the maximum and minimum temperatures of a day. One of my product manufacturer clients has a DTR limitation on the use of its product. Can you point me to other building products that have a DTR limit? I would like to see how others treat the situation in their product literature. Also, have you had DTR problems with a product or assembly? Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru John Bunzick Senior Member Username: bunzick Post Number: 1841 Registered: 03-2002 Posted on Thursday, March 25, 2021 - 03:20 pm:    That's interesting. There must be greater concern about the temperature change over a short duration than long. I would think some regions have a greater daily range, but lower annual range, and others have a higher annual range, but lower diurnal range. Can you tell us what kind of product this is? I have not heard of this before, only an overal range of temperatures. ken hercenberg Senior Member Username: khercenberg Post Number: 1353 Registered: 12-2006 Posted on Thursday, March 25, 2021 - 03:47 pm:    Michael, how is the DTR expressed? Is there a range based on material thickness? I'm trying to visualize when something like this comes into play. Perhaps having a ribbon window between cast-stone below and brick above and pretending that the continuous sealant joints at head and sill will survive a mid-Atlantic day that starts in freezing temperatures and ends up in the 80s or 90s or vice versa. I suppose a laboratory condition where liquid nitrogen is used would be about as extreme as any condition I've seen. Just setting a canister down on the floor could result in some pretty significant damage. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 594 Registered: 10-2003 Posted on Thursday, March 25, 2021 - 03:50 pm:    John - The product is new and not widely available, yet. The manufacturer is fortunate to have learned about a potential defect during early field trials. I don't want to share more because the firm is still trying to define it and engineer a solution. Until they do, I have been asked to propose language that should be included in their technical literature. I know that temperature swings can be a problem with all sorts of assemblies where components have different rates of thermal expansion. I am used to specifying maximum and minimum temperatures, and any Delta T constraints, but I have not heard of this related to diurnal cycles. Here are some of the parameters being investigated: - The problem seems to occur when DTR exceeds 20 degree F. If we look at the maximum DTR that occurs over a multiple year period, most of the US is affected. - Is performance affected by the speed of change? For example, a day's maximum temperature will typically be in late afternoon, and the minimum temperature just before dawn; the diurnal swing occurs over a 10 or 12 hour period. But when a weather front moves in, the ambient temperature can drop 20 degrees in less than an hour. I suspect the rapid change is more damaging than the gradual change. - Is performance affected by whether it is a hot day or a cold day? For example, does a change from 100 to 80 degrees on a hot day affect the product differently than a change from 20 to 0 degrees on a cool day? - Sun exposure: Direct sunlight will increase the temperature of a product mounted on the exterior of a building, especially on the west side of the building. Areas with shading devices may have less DTR. - Color: Dark-colored products will gain more solar heat. If a light-colored product is installed on a dark-colored conductive material, heat from the conductive surfaces can transfer to the product. - Wind: Wind can have a chilling effect, a factor not included in ambient air temperatures. - Height: According to one reference, DTR is typically measured 1.5 to 2 m above the ground. I suspect that products installed near grade may have smaller DTR due to the thermal lag of the earth. But this might vary if the ground surface or paving is dark colored and exposed to direct sunlight. If you know of any good resources on the topic of DTR, or have experience dealing with it, let me know. Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 595 Registered: 10-2003 Posted on Thursday, March 25, 2021 - 03:56 pm:    Ken - The scenarios you describe seem more like thermal shock, not the gradual thermal cycling. The problem appears to be within my client's piece of equipment, not due to the relationship between the product and adjacent construction. Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 391 Registered: 08-2004 Posted on Thursday, March 25, 2021 - 04:37 pm:    Michael, Interesting issue. Thanks for sharing with us. -