[Bldg-sim] Tall Bldg Infiltration

[Varkie C Thomas]

Proj-14 – Tall-Bldg – Infiltration due to Stack-Effect. 
 
Project -14 (Tall-Bldg – Infiltration due to Stack-Effect) is shown in website http://bepan.info/, tab “Proj-Bldgs” http://bepan.info/proj-bldgs and click “P-14-Tall-Bldg-Press” http://bepan.info/proj-bldgs/p-14-tall-bldg-press
 
The methodology of the Excel program shown in the website.  It calculates the infiltration in vertical section floors of tall buildings taking into account stack effect for each section. Wind Velocity and Direction was not considered so all exposure orientations are equivalent.
 
Excel program examples and summary for 85-story and 180-story buildings in Minneapolis and Dubai are shown in (open or download):
2a - Tall-Bldg-Infltr - eQUEST & Excel-Program-Summary - 85 & 180 Flrs
2b - Tall-Bldg-Infltr - Excel-Program-Example - MINNEAPOLIS - 85-flrs
2c - Tall-Bldg-Infltr - Excel-Program-Example - MINNEAPOLIS - 180-flrs
2d - Tall-Bldg-Infltr - Excel-Program-Example - DUBAI - 180-flrs
 
The stack effect theory and psychrometric equations used are shown in the example Excel files sheets “Bldg-Stck-Eff-Theory” and “Ref-Psychro-EQNs
The two buildings were also analyzed with eQUEST. Open or download:
eQUEST-Input - AutoCAD-DWG - Tall-Bldg - 320'x260' bldg
eQUEST-Input - PD2-File - Tall-Bldg - 85-Flrs - Stack-Effect-Infiltr - Minneapolis
eQUEST-Input -INP-File - Tall-Bldg - 85-Flrs - Stack-Effect-Infiltr - Minneapolis
eQUEST-Tall-Bldg - 85-flrs - BEPS, LV-B, LS-A, LS-C – Reports - Minneapolis
eQUEST-Input - PD2-File - Tall-Bldg - 180-Flrs - Stack-Effect-Infiltr - Minneapolis
eQUEST-Input -INP-File - Tall-Bldg - 180-Flrs - Stack-Effect-Infiltr - Minneapolis
eQUEST-Tall-Bldg - 180-flrs - BEPS, LV-B, LS-A, LS-C – Reports - Minneapolis
In the eQUEST program a vertical section is shell. 
 
Several articles and research papers on this topic are included in the zipped folders:
1 - ASHRAE-Tall-Bldgs-Stack-Effect-Press-Infiltr
2 - High-Rise-Apt-Bldgs - Ventil-Exhaust-Infiltr
3 - Tall-Bldgs-DOC - Press-Infiltr-Stack-Effect
4 - Tall-Bldgs-PDF - Press-Infiltr-Stack-Effect
5 - ASHRAE-NIST-PNNL
6 - Double Wall Facades
7 - Building Envelopes
8 - NIST-CONTAM - LBNL-COMIS Documentation
 
A typical High-Rise Mixed-Use used for teaching is shown in website http://bepan.info/ and tab “Proj-Bldgs” http://bepan.info/proj-bldgs and click “P-14-Tall-Bldg-Press” http://bepan.info/proj-bldgs/p13-high-rise-bldg 
 
The vertical sections of the examples include (1) ground-lobby, (2) retail, (3) financial, (4) general-office, (5) hotel services, (6) hotel rooms, (7) apartments, (8) dining-miscellaneous. 
 
The sections are not identical.
Each section used different floor plans & envelope types.
Different envelope types were selected from the CONTAM library for each section. 
The envelope properties are from NIST’s CONTAM library.
5a - CONTAM-Library - Enclosure Leakage Areas (Infiltr-Flow at Press-Temp)
5a is an Excel program that converts the CONTAM leakage areas into infiltration flows at different indoor-outdoor pressure & temperature differences in SI and IP units.
5b - CONTAM-Library - from NIST - Enclosure-Leakage-Areas
5b is the original leakage areas in the CONTAM library.
 
To do this for 8760 hours in an energy program would require excessive execution relative to the significance infiltration energy compared to total energy which is about 1% in summer and 12% in winter for a cold climate like Minneapolis. 
 
Program description is shown in:
3a - Tall-Bldg - Stack-Effect-Infltr – Excel-Program - User Guide - Report
3b - Infiltration in Tall Buildings - DOE21E & eQUEST Analysis
3c - Figures - Excel Program User Guide - Infiltr in Tall-Bldgs
 
The Excel program uses pressure, temperature & humidity conditions indoors & outdoors but does not take into account wind velocity and direction and therefore exposure orientations. Outdoor temperature is calculated for altitudes based on the ground design weather for summer & winter. 
 
It shows how to obtain € (To-Ti), € (Wo-Wi) and € (Ho-Hi) from 8760 weather file
This method of € (To-Ti), € (Wo-Wi) and € (Ho-Hi) from 8760 weather file is equivalent to 8760 hour calculation of energy programs as shown in:
4a - The € method is equivalent to 8760 hour calculations of energy programs
 
The energy estimate of infiltration is based on:
DESIGN DATASUMMERWINTER
Indoor DB (F) = Ti7572
Indoor RH %) = RHi5035
€(To:Ti) for 8760-hrs7,654250,474
€(Wo:Wi) for 8760-hrs7.7316.81
€ (Ho:Hi) for 8760-hrs8,81775,425

Indoor humidity ratio Wi (lbs/lb) and enthalpy Hi (btu/lb) is calculated from the dry bulb temperature (Ti) and relative humidity (RHi)
 
The difference between indoor and outdoor Temperature (To-Ti), Humidity Ratio (Wo-Wi) and Enthalpy (Ho-Hi) for summer & winter conditions for 8760 hours is required for the Tall-Bldg-Infiltr Excel program. 
 
Instructions for obtaining these values are under “C1c –Excel Weather-Analysis of Converted DOE2.bin file”.  Go to website http://bepan.info/  and then http://bepan.info/weather    and open or download:
Using Q€(To~Ti,Ts), Q€(Wo~W,Ws), Q€(Ho~H,Hs) apprx = 8760-Hr-Calcs
1 - TEMPLATE - DOE2 BIN Weather to Excel & Analyze
2 - TEMPLATE - Sum (Ti,Ts~To, Wi,Ws~Wo & Hi,Hs~Ho) 8760 Hrs
3 - LOCATIONS - Sum (Ti,Ts~To, Wi,Ws~Wo & Hi,Hs~Ho) for 8760-hrs
 
The program requires converting DOE2 8760-hour “Weather.bin” binary file to a “Weather.ft” text file using the DOE2 weather processor, and then converting the text file to an Excel file “Weather.xlsx”.  Go to website http://bepan.info/  and then http://bepan.info/weather    
Under “C1a - INSTRUCTIONS - DOE2 Wthr - *.dat - *.bin - *.xls” open or download:
9 - Weather _NCDC.tpe to DOE2.bin to Tables-Charts
11 - Template - Shanghai – DOE2-Weather-Analysis - Short
12 - Template - Beijing – DOE2-Weather-Analysis - Long

“Weather.epw” must be first converted to “Weather.bin” binary file.  Instructions are under:
“C1b - INSTRUCTIONS – Converting EnergyPlus Weather Files”
1 - Convert Energy-Plus.EPW to DOE2.BIN
2 - Convert EPW Text File to Charts-Reports
5 - Original - USA_MN_Minneapolis-St.Paul.Intl.AP.726580_TMY3.epw
6 - Edited - USA_MN_Minneapolis-St.Paul.Intl.AP.726580_TMY3.epw
7 - Read Text File into Excel - EPW-Minneapolis.xlsx
8 – Template-Excel - Minneapolis - EPW-Weather-Analysis.xls
8 – Template-Excel - Minneapolis - EPW-Weather-Analysis.xls
 
It shows that:
(1) % Infiltration in large commercial tall buildings is about: 
Less than 1 % in Summer, and about 15 % in Winter
(2) Lights & Equip is 60 % of total energy in summer and DHW is 10 % of total energy in winter
(3) For different types envelopes (selected from the CONTAM library) the infiltration per envelope area is between: 
0.02 and 0.09 cfm per sqft of envelope area in summer 
0.04 and 0.16 cfm per sqft of envelope area in winter 
using stack effect & varying the outdoor conditions due to elevation
(4) The infiltration cost ($)/year is: 
$138,065 ($0.21/sf Envelop-Area) for the 82 floor-bldg and 
$809,768 (($0.48/sf Envelope-Area) for the 177 floor-bldg. 
It is based on $0.15 per kwh for electricity and $0.75 per therm for natural gas.
(5) eQUEST default is 0.038 cfm per sqft summer and winter for all envelope types.
 
The envelope properties are from NIST’s CONTAM library.
5a - CONTAM-Library - Enclosure Leakage Areas (Infiltr-Flow at Press-Temp)
 
Below are some of my views:
Modern tall bldgs envelopes are steel-frame and glass (very light).
The envelope panels are manufactured off-site to exact dimensions using numerical control machines that allow for glass & frame expansion & contraction for the site location.
Also the requirement for entrance vestibules with a revolving door on the outside minimizes the stack effect infiltration in tall bldgs
There is less leakage in these bldgs compared older bldgs such as the 102 Empire State Bldg in New York built in 1930.
 
For air-conditioned pressurized bldg, the infiltration in summer can be neglected compared to the internal & other external loads.
I think stack-effect infiltration-exfiltration applies only to very tall bldgs.
For all other bldgs is no need to go to all this trouble.
Infiltration is greatest during cold weather when the air outside is denser than the dry air inside.
 
Wind velocity and direction also makes a difference. 
There is infiltration in a pressurized bldg even in cold weather.
Infiltration air enters from the windward side and exits from the leeward side (exfiltration)??
In summer the colder air inside is denser than the hotter air outside.
Infiltration is still a factor in pressurized bldgs even in summer.
 
There other specific issues that can be analyzed independently of 8760 hour energy programs.  Go to website http://bepan.info/  and then tab “Engg-Calcs”  http://bepan.info/engg-calcs to review some Excel programs that were created to study problems associated with particular projects such as.
1a - LCCA-Economics-Tables-Generator
1b - LCCA-Life-Cycle-Cost-Analysis
1c - LCCA-Lighting T5 versus T8 Cost
2 - Altitude VS Air-Properties
3a - Design-Weather-Generator
3b - PV-Solar-Radiation-Calculations
3c - Envelope-Radiation-Loads-Estimate 
 
Also under tab “Design” are preliminary databases that can be developed and expanded such as: 
2 - Design-Standards
3 - Design-Criteria
5 - Energy-Savings-Options
6 - Typical-Utility-Rates
7 - Bldg-Cost-Data
11 - Pipe-Sizing-Data
14 - Pumps-Fans
 
The website includes my notes for graduate courses and assisting Ph.D. candidates in “Energy Efficient Building Design”.  The objectives are shown in http://bepan.info/contents Open or download:
1 - BEPAR OBJECTIVES (draft for review at IIT-meeting 11-4-11
2 - BEPAR Proposed Database Organization & Forms to Submit Case Studies
BEPAN - OBJECTIVES:
(1) Develop case studies for different types of buildings with energy conservation options using different energy analysis programs. A statistical database of building performance by building types can be useful to A-E firms as a reference guide in the design of, and for projecting the performance of new buildings.
(2) Develop case studies of campuses and townships. Campuses & townships can save energy by using cogeneration plant for power and HVAC. Example: Life Cycle Cost Analysis (LCCA) comparing the present IIT campus Mechanical-Electrical Systems with a proposed central system that includes a Cogeneration plant for power and HVAC - http://www.iit.edu/about/campus_map.shtml
(3) Develop courses and graduate programs in energy efficient building design and would emphasize design practice using case studies. The two year graduate programs can be taught part-time by adjunct faculty working full-time at A-E firms if the basic teaching notes are developed by the group.
(4) Develop research topics by Academia in A-E design submitted by A-E design firms. A-E design firms cannot justify the overhead cost of Research & Development but a Group representing A-E design firms can accomplish this with the support of academic research institutions.
Varkie
http://www.iit.edu/arch/faculty/thomas_varkie.shtml
 
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