Where is the Dew Point

1. Where is the Dew Point

2. Attendance • Where did the word plumbing come from? • A) A man with paints hanging down and his crack showing • B) A Roman • C) A Greek • D) The Plumb Bob

3. Attendance • Latin word for lead is plumbum, from which we derive the words plumber and plumbing. • Plumbing refers to the specific water and sewage devices and systems of a building, while water and sewage systems refer to the systems that supply a group of buildings or geographic area, such as a city.

4. Attendance • Some of the best preserved evidence of ancient plumbing, however, was found in the excavations of Pompeii and Herculaneum. In 79 AD, a volcano known as Mount Vesuvius experienced a massive eruption, burying the cities of Pompeii and Herculaneum under a thick layer of lava and ash.

5. Attendance • The Romans were not the only people in the ancient world to have excellent plumbing by the standards of the day. King Minos of Crete has a primitive flushing water closet in 1700 BC. The kings of Crete were well known for their extravagant baths with hot and cold running water.

6. Where is the Dew Point?

7. Need to Know • Which criterion used to assess your work as a professional has the greatest potential to increase your firm’s net profit? • A. Having a project which is LEED certified • B. On time, on budget project • C. Lowering the client’s energy costs • D. Improving employee productivity • E . Meeting/exceeding client expectations

8. Need to Know • What is the first step in designing a high-performance building? • A. Identify synergies • B. Select the correct HVAC system • C. Design around human comfort • D. Find the design Criteria of the system needed per ASHRAE Standard 55 • E. Reduce the load

9. Where is the Dew Point? • First I start off as water vapor

11. Where is the Dew Point? Inside temp. 720 Out design temp. -40 RH = 40% inside RH = 20% outside 570 = Saturation Temperature

13. Where is the Dew Point? Formula for Temperature at Assembly Parts Inside Temp. – (( R value / Total R )x Δ T)

14. Where is the Dew Point? Inside temp. 720 out design temp. -40 720 – (-40) = 760 Total R value = 22.27 Inside Air Film 0.68 Temperature at surface of inside wall. 720 - ((.68 / 22.27) x 760)) = 69.680

15. Where is the Dew Point? Inside temp. 720 out design temp. -40 720 – (-40) = 760 Total R value = 22.27 5/8" Gyp.Bd. =.56 Temperature at surface of inside wall. 69.680 - ((.56/ 22.27) x 760) = 67.770

16. Where is the Dew Point? Remember …..570 = Saturation Temperature! If there is any moisture in the wall, where will it condense and where would it freeze?

17. Where is the Dew Point? Inside temp. 720 out design temp. -40 720 – (-40) = 760 Total R value = 22.27 so at 570 where is that in relationship to the water vapor condensing within the wall? 720 - (X/ 22.27) x 760) = 570

18. Where is the Dew Point? 720 - (X/ 22.27) x 760) = 570 (720 – 570) = (X/22.27 x 760) 150 = (X/22.27 x 760) 150 /760 = X/22.27 .1970 = X/22.27 X = 4.39

19. Where is the Dew Point? X = 4.39 What is 4.39? Batt insulation is R-19 @5.5” then k = 3.45 per inch So 4.39 is about 1 -1/4” into the batt insulation and that is where the temperature is 570. 4.39

20. Where is the Dew Point? More importantly, that is where the water vapor will condense and become water at about 1-1/4” into the wall when the outside temperature is -40

21. Then where is the Freezing Pointin the wall? 1- 1/4” 320 570

22. Where is the Freeze Point? Inside temp. 720 out design temp. -40 Temperature at surface of inside wall. 720 - ((X/ 22.27) x 760) = 320 Same math as before 720 - (X/ 22.27) x 760) = 320 (720 – 320) = (X/22.27 x 760) 400 = (X/22.27 x 760) 400 /760 = X/22.27 .5260 = X/22.27

23. Where is the Freeze Point? X = 11.71 720 - ((11.71/ 22.27) x 760) = 320 So if R-19 has a k value of 3.45 per inch, water will freeze at about 3” into the insulation.

24. Where is the Freeze Point? 1- 1/4” 320 3” 570

25. Where is the Freeze Point? • Once the water condenses in the wall or ceiling we have problems!!!!!!!!!!! • Much Like……

26. Where is the Freeze Point? this little cute creature becomes…..

27. Where is the Freeze Point? This!

28. Where is the Freeze Point? If the water could continue its journey and escape outside the backside of the brick to the cold minus -4 0 outside temperature, the following formula substantiates that assertion. 720 - ((22.27/ 22.27) x 760) = - 40

29. -4 degrees

30. Where is the Dew Point? • Positive Pressure Where within the building, and what time of the year would we design positive spaces. Make sure we do not have positive spaces on outside walls in the winter months!