HVAC/IAQ lab formula

Hi everyone,

Two comments:
1) We got a question from a student and am posting the response here in case others are having the same problem:

Q:  In the Week Four HVAC/IAQ Lab Instructions, the equation for energy carried by airflow only shows up as

Eairflow=m×[]
when I download it.

A: The formula for Eairflow is m*[0.24T+W(0.45T+1061)]

Where m should be m with a dot over it as the mass flow rate, T is the temperature, and W is the relative humidity as described in the parameters of question 2 of the Excel file.

2) EDITED: I had a previous comment here before which was incorrect, sorry!

-Anita

Grading Notes–Attendance and Calculation Method

I’ve brought the attendance grades up to date through week-4.  You should check the attendance score and other grades now rather than at the end of the term.

Notes on the grading:

• Attendance scores are “raw”.  At the end of the term I will make an allowance for one missed lab and two missed lectures – a total of three.  This will improve your attendance score in the final grade calculation.
• Discussion and Lab scores are already adjusted to drop the lowest score in calculating the running total. 
• HOWEVER.  If you didn’t turn in a lab or discussion that one isn’t included in the calculation during the term.  IT WILL be included as a “0” at the end of the term so your overall grade could decrease

Week-4 - Rec Center Tour - Lab Locations and Times

This week we’ll be touring the Rec Center AND having time in the lab to address the calculation assignment of the week.  You should plan to be involved the whole two hours of your lab period.

Note that we will meet outside the East entrance to the Papadakis Integrated Sciences Building (PISB) (inside if raining).  Here’s a map showing where we’ll meet and where we’ll go.

• Wear flat shoes (NOT heels) – we’ll walk on sensitive surfaces.
• We’ll take attendance during the tour

 

Time & Location

Lab	Last Name	Time	Location	2nd Hour
060	A-L	10:00	PISB	Randel-327
060	M-Z	10:00	Randel-327	PISB
061	A-L	12:00	PISB	Randel-327
061	M-Z	12:00	Randel-327	PISB

Hydrology lab corrections/clarifications

Hi everyone,

Just a couple important notes from issues that came up in lab today:

A) On the Excel file, question 2, the first line is supposed to be an example.  However, it is incorrect on two counts.  First, the data you inserted from rainfalldata.xlsx has rainfall data for 1/1/12, and that should be included in your calculations.  Second,  "Outputs" (column E) and "Amount supplied by the municipal supply" (column H) are incorrect for that day.  The outputs in ft^3 should have a value of 1604 (but be sure to show your work, 0 credit will be given for typing that number).

B) It has now been fixed, but if you downloaded a copy of today's lab lecture notes before around noon today, there's a typo on the 4th slide: the volume of the cistern should be calculated as 15000+750*LettersLastName, not 1500+ 750*LettersLastName.  Sorry for the confusion, if you see any other such contradictions, please ask for clarification - we do make mistakes!

C) The rainfall.xlsx file has two tabs: one has the precipitation in inches, the other tab has different units.  You'll get the same answer if you use the correct conversion for each case, but please be aware of the difference - starting with the values in the inches tab will be easiest.

D)  Please note (as the instructions do) that for question 3, the x and y axes should be labeled, and that you need two separate plots.  In the example, the x-axis is day of the year, but there are many ways to display the date, you may choose a different one.

We've also gotten a few questions about the lab feedback on BBLearn: when you look at the assignment on BBLearn, the preview you see is for what you submitted, not our responses.  To see the responses, click the file on the right side, should be a file starting with your last name and ending in "graded" or "grd"

Please let us know if you have any questions!  We would much rather answer your questions before labs are due than take off points while grading.

-Anita

Lab 1 feedback and notes on memos

Hi everyone,

We've finished grading the first lab and you should be able to see your grade and download our responses via BBLearn.  If you have any questions, let us know or talk to us in class on Friday.

A few general comments: 
- You should NEVER type values into Excel, with the rare exception of multiplying or dividing by 1000 (like changing to kips in this lab).
- Lots of points off for sig figs and notation: 2 to 3 sig figs will be criteria for the entire term
- Name and date on each page: if the header is not visible, switch to page layout view

And a few notes on the memo: 
- It is 100% okay to be direct and say "The purpose of this lab was __" and then continue on from there.
- If you're stuck on what to write for the purpose or details section, look again at the grading criteria for each question: if we're looking for it in the grading criteria, chances are we wanted you to learn something from it.
- For details, you do not have to provide details for every question, it should be a summary, not a step-by-step procedure of what you did.
- The implications and limitations are an attempt to have you look at the lab in a broader view.  Think about: what are the broader consequences of what you learned (will you use it in the future? do your results indicate success or failure? how does this type of system work?) and what kept you from being more accurate or certain about your results? (did you make simplifying assumptions that are too simplistic? what piece of data was limiting? where do you think the largest source of error comes from?)
- These should have a formal tone, and should never be in first person.  A previous TA used this great example: "We took a tour of the Tacony-Palmyra Bridge and it was so fun to get hands-on experience and measure the strain gage distance for ourselves."  A better way to state the same activities: "A site tour of the Tacony-Palymyra Bridge was conducted and field measurements were recorded to determine the strain gage distance."

If you're having problems with the memo, somegreat source for writing business memos:
http://owl.english.purdue.edu/owl/resource/590/04/

http://www.writing.engr.psu.edu/

You can always get help here at Drexel by utilizing the Writing Center:http://drexel.edu/engphil/about/DrexelWritingCenter/http://drexel.edu/engphil/about/DrexelWritingCenter/workshops/
They also have various workshops you may register for during the various terms:http://drexel.edu/engphil/about/DrexelWritingCenter/workshops/

Please remember to include all three documents (.rvt file, .docx file, pdf) when you submit your Revit lab this week!

See you back in the normal classroom this week, Randell 327,
-Anita

Lab-1 - Help with Question 5b

Question

“would the first blank where it asks for the Air BTU/CF-DegF be solved by dividing the air specific heat by the air density?”

Response

There are several ways to address this kind of problem where you’re facing new material.

1) Check the units.  Given the information available what combination produces the units of the desired answer.  In this case that’s BTU/CF-DegF.

2) Think about the physical reality – the more meaningful approach.  I suggest thinking about one cubic foot of air. 

• What do we know about it? 
• It has a mass, which we can calculate with the given information
• It will take a amount of heat to raise it one degF
• We can calculate that if we know the mass because of the other given information
• With those two you have the answer
• The same approach will give you answers to the other parts.

Revit Lab–Hints for the Lab

Below are the hints for the lab.

• Save your file to desktop in the cadlab to avoid losing it in your machine 
  • Email it to yourself, or use a flash drive, or DropBox
• Videos online are helpful if the text instructions aren't clear
• If you have only 3-4 letters in your last name - multiply by 20 to get the length of your wall.
• Make walls go to 2nd level 
  • set "property" before  drawing, but you can change later
• Remember to put on a dimension 
  • under the annotate menu
• Not all things in the videos are required for this lab

Suggestions About Using Revit

Questions: – From Previous Year, but still appropriate

1. Hello, I have one question about the Revit Lab. I followed the videos, made the Revit model and the output sheet. How do I convert the sheet to a PDF file from Rivet?
2. Also, we're supposed to submit the actual Rivet model, meaning we have to submit the actual file we made upon starting the Rivet videos? Just a little confused, hope you can clear that up thank you.

Response

#1 You need to “Print to PDF”.  On the machines in the lab there is a PDF printer installed – just choose it when you’re printing.

If you’re doing this on your own machine you’ll need to install a “PDF Printer”.  There are multiple free one available.  TechSupportAlert is a good recommendation source – Here’s their link to PDF Printers and tools.

#2 You are to submit three things for this assignment

• The actual Revit File
• The PDF of the “Sheet” that you’ve created
• The Word document defined in the assignment.

Discussions–How Many Other Students to Review?

Question

If we posted first in our thread, do you still want us to reference other students' posts?

Response

I’ve revised the discussion page to address this question explicitly.  Here’s what it now says.

Each week you are to prepare for the week by reading two professional-level sources that give material related to the topic for the week.

You are to answer some standard questions about it and give some opinions.

You will enter that into one of the discussion "topics" for that week in BbLearn. You are also to read the entries of other students who have read the same primary source material and react to those entries in an appropriate way by editing what you've written to react to what those before you in your topic have entered.

We expect you to comment in some way in your discussion post on the work of at least two other students.

• If you're the first to post in your thread you do not need to comment on other student's work - but you do need to state that you were the first to post.
• If you're the second to post you comment on only one.
• We'll check and deduct points if we find suspicious claims.

Lab 1 tips

1.       Due - 10 AM Friday a week after the class, for both sections.

Excel:

2.       Named Variables - don't use spaces. Good practice -- capitalize 1st letter of a word, e.g. MyFirstName. If you need to eliminate an unwanted named variable use Ctrl-F3 shortcut.
3.       Troubles with Excel -- please refer to Excel help and tutorials; it is the best and most effective solution. You can also try the IRT MS Office on-line training.
4.       Remember, Excel is a computational software; it is designed to do computations for you.
5.       Excel allows leaving comments in cells - you can use this feature when you feel a comment may add clarification.
6.       Consult the Post-It-like notes and Instructions attached to question pages for grade tips.

Units and sig figs:

7.       Conversion factors column does not need formulas; it needs conversion factors which are constants. No real rule for conversion factors sig figs.
8.       Units spelling -- refer to literature e.g. , NIST Handbook 44 - 2013 Edition, Appendix C -General Tables of Units of Measurement  OR NIST Special Publication 330, 2008 Edition. International System of Units (SI). Both are by National Institute of Standards and Technology, Washington, DC.
9.       Note:: Some questions have non-conforming unit notations, it is alright to correct them when Excel allows to.
10.   In Question 5 --  BTU/CF-DegF means Btu/ft³∙°F (and similar to it cells).

Memo:

11.   Writing Memo -- consult Prof. Mitchell's blog entry and the links he refers to.
12.   Memo subject -- "Meaningful phrase that announces the topic".
13.   Memos should have a professional tone. Limitations of the lab are not your own personal limitations or struggles but rather specific caveats related to assumptions you had to make in order to complete your calculations (ex: did you actually measure your shoulder width with a ruler?) See the earlier entry on the course blog for additional suggestions.
Misc.:
14.   If you do not have a laptop, please look at the lab prior to class time and come to the class session to ask your questions.
15. If your computer does not have MS Office -- it appears that it is OK to do it in OpenOffice (save as .xls or .xlsx file), or maybe use CADLab machines.

Conversion Factors and Methods

Conversion factors could be seen as universal constants. Some of them are exact, like 1 inch equals 25.4 mm. Most of them don't have an exact value but rather expressed as a decimal fraction with 4-8 sig figs which is enough for most engineering applications without reducing desired precision.In the lab we had to find several conversion factors. It may be OK and definitely convenient to google it, but for the lab Memo and for professional reports a google search result is not a credible reference. The best source of reference materials such as conversion factors is a relevant industry's handbook. For HVACR it would be ASHRAE Handbook - Fundamentals. An electronic edition of it is available through Drexel libraries, but for this large class' convenience I also supply a link to the Chapter 38 image file on my Google Drive. I hope the ASHRAE people won't be considering it as a serious breach of copyright. It can be cited   (2009), 2009 ASHRAE Handbook - Fundamentals (I-P Edition), Chapter 38 Units and Conversions, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Another great reference would be ASTM/IEEESI-10-1997 Standard.
The unit-factor method is a commonly used technique to convert a value from one system of units into another, or from one unit into another within the same system. Explore it more on KhanAcademy videos. Wikipedia article on it is also a good explanation of the unit-factor method (and of course we never refer to Wikipedia in memos and reports).

Significant Figures and Rounding

   The concept of significant figures (sig figs, s.f.) arises from the concept of physical measuring of a variable. Instruments we use have finite accuracy and reliability. For example, a desk ruler has least readable unit (least count) of 1 mm, while a common Vernier caliper can measure with accuracy of 0.02 mm. Thus the reasonably reliable length of a steel plate measured with the ruler could be 26 mm (two s.f.), while measured with the caliper would be 26.14 mm (four s.f.). If one has to add two measures, let's say a plate measured with a ruler and a plate measured with the caliper, the ±0.5 mm uncertainty of the first plate will dominate the uncertainty in length of the second plate ±0.01 mm. When that person reports the combined length of 52.14 mm he or she cannot defend the final precision up to 0.02 mm because the ruler's precision of 1 mm dominates.Side-note: some technicians and researchers state that many elementary measuring devices allow an (experienced) operator to estimate the measured value one figure beyond the instrument's least count. In our ruler example, we could estimate the plate's length as 26.1 or 26.2 mm (three s.f.)

   Very often we have to use the measured values in various calculations which ordinarily give as answers with a long trail of decimals. While it is perfectly fine to carry the trails during a multi-step calculation, the final answer must be always rounded off and reported with a correct number of s.f. In other words, the accuracy of the final answer cannot exceed the accuracy of the least accurate measurements or data provided.  Four groups of different arithmetical "operations" have different rules of maintaining s.f. Those groups are Addition and Subtraction, Division and Multiplication, Logarithms and Antilogarithms, and Trigonometric functions.

   Addition and subtraction can produce and answer with a higher or lesser s.f.

   Division and multiplication results are limited by the data with least s.f. I have heard respected opinions that there's an exception to the division and multiplication rule. The opinion is based on the notion of fractional uncertainty: when an answer begins with a digit 1, the answer's accuracy would be preserved better if we maintain an extra s.f. than the original data with lowest s.f. I personally adhere to that opinion. However, I advice to proceed with caution - it appears that this "rule of 1" is not widely discussed and often omitted. Please consult relevant literature or specific industry's guidelines for further use.

   In logarithm operations the mantissa determines the number of s.f.

   For purpose of real life applications trig functions preserve the number of s.f. of the input variable.

   A few words on rounding tie-breaks (when the "digit" we want to cut off is "exactly" 5, e.g. 26.145 or 26.14500 or 26.145000). Many disciplines use the round half up or round half away from zero rules. Both those rules are asymmetrical and lead to biases. In science the most accepted tie-breaking rule is round half to even. As per 09/25/2013 1900 the Wikipedia's relevant page has a correct explanation with an example.

   My favorite intro text on s.f. with computational examples is Quantitative Chemical Analysis by Daniel C. Harris.

References:

ASTM Standard E29, 2008, "Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications," ASTM International, West Conshohocken, PA, 2008, DOI: 10.1520/E0029-08, www.astm.org.

Harris, D. C. (2007), Quantitative Chemical Analysis, 7 ed., 663 pp., W. H. Freeman, New York.

Michener, B.; Scarlata, C.; Hames, B. (2008). Rounding and Significant Figures: Laboratory Analytical Procedure (LAP). 7 pp.; NREL Report No. TP-510-42626. http://www.nrel.gov/biomass/pdfs/42626.pdf

Discussion Posts–Addressing Other Student’s Work

Question:

I would like some clarification about how you and/or the graders would like us to respond to other students posts. Should we use the "Reply" button underneath another students post, or should we include our responses in the body of our own post?

Response:

You want to make sure the grader knows that you have read and considered other people’s work.  The best way to do so is incorporate references to other people’s posts in your own post.

• e.g…… I agree with Jonathan Doe’s opinion about the importance of Geotextiles in Geotech, but am concerned that we don’t have good data on how they will deteriorate over time…………

Week-1 &2 Lab Schedule Information

Week-1 - In the Default Space – Randel-327 (corrected 4/3/2014)

• Bring your laptop or other device on which you can work with an Excel Speadsheet
• Look at the lab beforehand - have your questions ready for the TA

*******************************************************

Week-2 - Revit Lab

Where: CAT-167A – Google Map

Because of the limited number of computers in the lab we’ll split the labs into 1-hour blocks

Times

Lab Section #	Last Name Begins With	Time
60	A-L	10-11
60	M-Z	11-12
61	A-L	12-1
61	M-Z	1-2

 

Bring

• Yourself
• Lab – Please look at it first
• Laptop if you’d prefer to work on your own machine