# Stack/wind pressure and flow networks.

Hello my first post,

I'm wondering if there is anyone about who could advise on the calculations involved in determining flow networks for natural ventilation. I'm studying a distance learning masters in sustainable design and there is something for this assignment I'm just not getting.

I've been through

A Guide to Energy Efficient Ventilation, Martin W Liddament – AVIC

Air Infiltration Calculation Techniques - An Applications Guide, Martin W. Liddament – AVIC

2009 ASHRAE® Handbook Fundamentals

Ventilation for Acceptable Indoor Air Quality, ASHRAEE standard 62.1

And several other presentations, book and publications.

and in part of this I found a couple of Discussions here that have helped but not fully covered what I need.

If anyone can help I'll go into more detail but the basic layout is below. Obviously I don't want to solution calculated for me as that would be cheating but just people to bounce off would be nice.

Views: 124

### Replies to This Discussion

Pascals for stack has been discussed to death here

Wind is pretty easy to find & if need be I would recommend googleing Bernoulli's principle on wind

Unfortunately just looking at the diagram without some context it is hard to know what you need help with

https://www.linkedin.com/groups/6942179/6942179-6030115404729307139           'm not sure this is what your exactly looking for Daniel but it should direct you to the right area.

I asked this question to Colin Genge really one of best minds regarding this in the business. Anyone can theorize but measuring is why most of us are here. If your going to measure one thing against another do it the same way every time. This escapes some in our industry...Anyway take the time to read what he wrote on set-up and join his group. Best of luck and share what you come up with.

Daniel,

I'm assuming you're trying to predict the airflows through the different openings W1, ... ? It is very unclear from the drawing. You're probably aware, but solving the problem requires calculating the pressure differentials at each opening, as they vary with height and temperature difference. The airflow is then simplified as an orifice flow, typically with flow and pressure coefficients that characterize the size and shape of the opening. Wind is trickier, but is generally treated similarly. I know the relevant equations are in the Liddament books, but can't remember specifically where.

So I wanted to start with a basic who can help then go into more detail later.
But yes find the air flows through the openings and area of the openings.

I've approached it now as airflow/m^2 of opening then used air rates per person (EN 13770:2004) to specify a target rate for winter and summer and size the openings from that.

This hasn't been the most precise and consistent course and assignment I've ever carried out.

My tutor got back to me and while areas don't quite feel right a little to much assumptions and things not quite adding up in the examples I'm slowly moving on.
We have a certain amount of freedom to manipulate the design so to simplify things I've closed off L1 as suggested by the tutor.
The thing that got me was having calculated the stack pressure based on the lowest opening and then added the wind how do I determine the flow networks.

The examples have the flow rates calculated end to end so combining the pressures W3 and L2 for the air flow right through the building. Treating each floor as individual zones.
Now the assignment is only meant to represent very early calculation estimates so I guess this is ok, personally I'd then move to use CFD software after the heavily simplified systems for better predictions.

## Featured Forum Discussions

### BPI Anaylist and installers

Started by Larry R Waters in BPI. Last reply by Quinn Korzeniecki on Friday.

### TREAT modeling of mid-rise apartments low heating load

Started by Jim Fowler in General Forum. Last reply by John Nicholas on Friday.

### What causes a temperature plane in a home

Started by Energy Wise Solutions in HVAC. Last reply by Brad Cook on Thursday.

### BDT with vermiculite in hollow CMU walls?

Started by Brad Cook in General Forum. Last reply by Jan Green Apr 15.

### Velocity Pressure Testing

Started by Horace Douglas Hunt, Jr. in General Forum. Last reply by Horace Douglas Hunt, Jr. Apr 15.

• View All

## Latest Activity

Crosbey Archery posted a blog post

### Can I know the Advantages of Solar Energy?

17 hours ago
Chris Woods added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase

### Minneapolis Blower Door Fan and Door frame \$990 OBO

I have a used Minneapolis blower door fan (fan only, no controls or panel) and the blower door…See More
Friday
Manuela L Heyn and Paul Nagel joined Home Energy Pros
Friday
"If you choose to buy new, give TruTech at call at 1-888-224-3437 option 1"
Friday
Home Energy Magazine's blog post was featured

### The Legends of Home Performance

A project long in the making, we're happy to finally reveal some of our Legends of Home Performance…See More
Friday
"Hi Larry, We're glad you're reaching out to hire some BPI folks! You can also submit…"
Friday
Larry R Waters posted a discussion

### BPI Anaylist

Industry leader in the north bay area California. Looking for experienced professionals and future…See More
Friday
Larry R Waters joined Diane Chojnowski's group

### Job Board

This group is for posting jobs related to all aspects of the home performance industry including…See More
Friday

## Events

• ### Better Buildings Peer Exchange Call: Multifamily Collaboration with NEWHAB: Smart Tech, Health, and Utility Data

May 4, 2017 from 1pm to 2:30pm – Eastern Time

• ### Better Buildings Peer Exchange Call: Are You Ready? Opportunities and Challenges of Home Energy Management Systems

May 11, 2017 from 1pm to 2:30pm – Eastern Time

## Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines