1st Tip:
ASHRAE (American Society of Heating ,Refrigerant and Air-conditioning Engineers)
We can use ASHRAE Standard 62.1-(2019, or any version )(Ventilation for Acceptable Indoor Air Quality ) for
extracting below Data which can not be neglected in any HVAC calculations :
1-Air Intake Minimum Separation Distance from any exhaust source According to its Air Class
2- Air Classifications (According to application)
3-Minimum Ventilation Rates(Fresh air Required) and it is divided to two parts
*Outdoor Air required for people
*Outdoor Air required for Area
also we can get No. of People in specific space according to its application.
4-Minimum Exhaust Rate.
Note:
*Please, Read each note after any table in ASHRAE very carefully.
*Notice that ASHRAE mentioned Minimum Rate Only.
*We can find different values in each versions so it is recommended to use update one
2nd Tip:
ASHRAE HVAC Application Guide -from its name we can find approximately all Building applications in this
guide , from comfort applications ,Industrial applications to Energy-Related applications.
each chapter is talking about one application such as (Design Concept , Design Criteria , system Required and
Special Considerations)
we can find internal design conditions that will result in comfort for each application such as below:
1- Indoor Desired Temperature.
2-Relative Humidity RH.
3-Ventelation Rate (Fresh Air).
4-Exhaust Rate.
5-Filter Efficiency.
6-Noise Level.
which will be Very important in Design proper HVAC system (Calculation input )and also selection of the right
equipment.
we will talking about each chapter in separate tip isAllah.
We only make a brief for each ASHRAE guide book till now.
3rd Tip:
ASHRAE Fundamental Handbook , it covers basic principles of all system used in HVAC starting from how to
use Psychrometric chart , refrigeration cycle , heat transfer , Energy Calculations, Sizing ,Materials to
sustainability.
So it means , if we need to start we can start from it, this code teaches us how to design what is design , and
why we design , in another word it start from design concept of a project (Building) to operation stage.
Using ASHRAE is not so simple so we will focus on important points and chapters ,also in my point of view one
of the most important points in ASHRAE is its Notes so please cares about it.
4th Tip:
ASHRAE 90.1 -- Energy Standard For Building Except Low Rise Building
At first we need to read any guideline title carefully as it is mentioned (Except Low Rise Building) , we will be
talking about building classification in a separate tip
But Now lets count the information that we can extract from this guideline and use it specially in our
calculations:
1-lighting Power Density
2-Min. Efficiency for several equipment used.
3-Min. Pipe Insulation Thickness.
4-Building Power Distribution System.
(1st point is very important because it has noticeable effect on our Energy Calculation as it is(Lighting)
considered one of internal heat gain source )
5th Tip:
ASHRAE Design Manual for Hospitals and Clinics
it provide us with a detailed source of HVAC design for hospitals and clinics , ASHRAE already have separate
chapter in ASHRAE applications (Chapter 06, 2011 ) which simply covers health care facilities application also
this guideline include all data mentioned in ASHRAE Standard 62.1
But here we have a a complete guideline for these applications which covers all design ,installation and
commissioning points for any project including :
1-Environmental comfort
2-Infection control
3-Energy conservation
4-Life safety
5-Operation and maintenance
here we have a separate chapter talking about terminology (describe all expression we can hear in this
hospital application)
this guide is so richy , important ,Challenging ease as opposed to other ASHRAE manuals you can enjoy
reading and extract data from it.
also we can be certified from ASHRAE only in hospitals and clinics HVAC design with (HFDP-Healthcare
Facility Design Professional Certification )
it may describe how much it is important , because here we are not search for comfort conditions only , but
also we control infection , and provide high air quality.
6th Tip:
SMACNA (Sheet Metal and Air Conditioning Contractors' National Association )
Simply it covers all data and information required for a proper duct design and installation.
we can find below topics in this manual :
1-Air Distribution
2-Various Methods of Duct Design
3-Pressure losses all over the system
4-Noise Control
5-Installation and materials
6-TAB (Testing, Adjusting and Balancing)
7-Cost
8-All charts and tables used in duct design
Notice that we already have chapter in ASHRAE Fundamental (Ch.21 Duct design) but actually we use SMACNA it
is more detailed and practical.
Duct System for any HVAC system is very important in:
1-Thermal Comfort
2-Humidity Control
3-Ventilation
4-Air Filtration
7th Tip:
HVAC Equations, Data and Rule of Thumb
in one simple word it is a Conclusion for all Equations and data you need in design (by practice and from
ASHRAE , SMACNA AND NFBA ) , we can find all input data we need in our calculations supported with
equations as below:
1-Definitions
2-Equations (cooling load , water sys. ,fan and pump power Expansion tank ,Psychrometric Equations and so
on )
3-Cooling and Heating load check figures (Ton per Ftsq.)
4-Infilerationa and Ventilation rate
5-occupancy , lighting and equipment rates
6-System Selection , Duct design and Air Distribution.
7-Piping system and central plant
8-Equipment Schedule data construction
9-Manufactures ,Electrical , structure and architectural information that we should know for proper design.
10-Properties for air and water
lets say we can use this guideline for extracting input data needed to construction , installation and operating
stage ,this is a simple way to understand and begin in HVAC works so it is recommended to be read.
Note:
we can hear this expression( Building efficiency ) based on its design , construction, operation etc. and one of
the most effective parameters is HVAC design.
8TH Tip:
NFPA (National Fire Protection Association)
NFPA covers important subjects for HVAC engineers listed below:
1-Ch.90
90.A ----Standard for the Installation of Air- Conditioning and Ventilating Systems
90.B ----Standard for the Installation of Warm Air Heating and Air-Conditioning Systems
2-Ch.92 ---- Standard for Smoke Control Systems
92.A ----Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences
92.B ----Standard for Smoke Management Systems in Malls, Atria, and Large Spaces
3-CH.96 ---- Standard for Ventilation Control and Fire Protection of. Commercial Cooking Operations
Note: CH92 is one of the most important chapters which discuss this topic.
we have chapter for (Fire and Smoke Management) in ASHRAE Application Ch.53
9th Tip:
Three and Two way valves:
-Three way control valve has three openings for flow , is best suited to applications requiring a constant flow
rate.
-Two way Control valve has two openings one inlet and one outlet , used in applications requiring a variable
flow rate.
we can use both valves in chilled water system depending on design concept and cost consideration.
-employing a 2-way valve at the outlet of the chiller provides the ability to modulate the supply to the cooling
load, depending on the load requirement. This can lead to cost savings, as the load on the secondary pump
will be reduced.
Note:
some engineers have some conflict between these valves function so mark it like that (3 way - constant speed
)
( C ) is the third letter in alphabets so ( C is directly connected with number 3 ) so simply ----- 3 way mean
Constant speed
10th Tip:
If we have high rise building one time as a Residential and the other as an Office Building(same building with
same design but two applications)
If we compare between them from Fresh Air Flow rate ,Which application will have the more capacity!?
from ASHRAE 62.1-they have the same fresh air rate (0.3 l/s-m2 & 2.5 l/s-person) but the occupancy is not the
same (for Bed room and Office for example) but in office building we have (Reception ,Break room ,meeting
room and so on )
if we count the occupancy for whole building in the two cases we will find that in case of office Building it is
more than Residential one so for the first look we can say office building is more for sure , but after making Air
Balance we will find that Fresh air required for Residential is more than Office Building ,simply because we
have exhausted spaces (such as toilets and kitchen) in the residential which need make up air on the opposite
in the office building.
So, when we have a recovery unit in case of office Building we need to extract exhaust from offices to increase
exhaust flow rate, on the other side in Residential we uses the exhaust from toilets and kitchen and there is no
need to extract air from any other spaces.
11th Tip:
Central Mechanical Equipment Room Location in high rise Building,
in high rise building we can make more than one mechanical equipment room (secondary set for chillers or
ETS room)
depending on building height ,Aprox. every 90m (20 to 24 floors ) we make a new secondary loop.
why it is necessary to do that : max working pressure for fittings and valves in market is 150 psi or 300 psi but
increasing working pressure in cycle (for all component )mean increasing cost and as we all know it is not
preferred.
so we go to the solution of dividing building every 90 m to a separate secondary loop or ETS room (Heat
exchanger and secondary pumps) so we can avoid failure in any equipment.
Ref. ASHRAE Design Guide for Tall , Supertall and Mega tall building systems CH.9 with case various study
some attached photos to clarify the tip from Ref.
12th Tip:
Refrigeration or Cooling Cycle
This is the basic but also the most important part of HVAC process , know how !
the main concept of Heat Transfer.
1-Evaporator : used to turn any liquid material into gas. In this process, heat is absorbed (Qin) .
2-Compressor :transform a low- temperature vapor in to a high-temperature vapor, to increase pressure. Through a
compressor, heat can be easily released or rejected (Qout).
3-Condenser (Heat Exchanger) :condenses the high-pressure refrigerant vapor from the compressor into liquid.
*Air Cooled
*Water Cooled
4-Expansion Valve :reduce the pressure and temperature of the refrigerant , sudden drop in pressure and
temperature produces a cooling effect.
If we reverse this cycle it will be a HEAT Pump Cycle
13th Tip:
Heat Gain Sources--it is affected by building type, site climate, and building design , consists of External and
Internal sources.
1-External Sources: heat transferred through building envelope (Walls , Windows , Roof , Doors ,infiltration and
floor)
2-Internal Sources: People , Appliances, Equipment and Lights
Total Load consists of Sensible and latent load
The sensible load affects the dry bulb temperature, while the latent load affects the moisture content of the
conditioned space.
14th Tip:
Expansion Tank - The expansion tank is a part of an overall chilled water system
Function:
1-Maintain thermal expansion of the chilled water through the cycle.
2-Maintain positive pressure at all points in the system at all times.
3-Maintain net positive suction head at the chilled water pump to avoid pump cavitation.
Types:
1-Open tank
2-Closed tank (without Diaphragm and with Diaphragm or Bladder)
A closed tank with a bladder or diaphragm is the most common expansion tank ,As the chilled water volume
expands the water pushes against the bladder or diaphragm. It serves as a barrier between the air and the
water to limit the air that can be entrained into the water. For example, the closed tank has a pressure of 14.7
psia. as the chilled water pressure increases above 14.7 psia, the chilled water will flow into the expansion
tank.
Location:
Tank is located at the CHWP suction, near the lowest point in the system because the pressure of CHW
system will be higher (it is not recommended to be located at higher point of system because sys. pressure will
be lower which result in low size of tank also for maintenance issues )
Note :
PLEASE FIND ATTACHED PIC IN COMMENTS
(Ref. The following article was published in ASHRAE Journal, March 2003.)
15th Tip:
Flow and Capacity calculation:
How we can simply say that Flow (GPM)=2.4 Load (TR)
it is depending on ΔT (Temp. diff.)
If we know basic formulas it will be so easy to calculate whatever we need.
Q = M × C × ΔT
Where
Q = Quantity of heat (Btu/hr)
M = flow rate (USgpm)
C = specific heat capacity (Btu/lb.F)
ΔT = temperature Difference of fluid (F)
1 TR= 12000 Btu/hr , 1 gpm = 8.33 Ibs
Assuming the fluid is water (C = 1 Btu/lb.F) , the formula takes the more common form of:
Load (Btu/hr) = Flow (USgpm) × (Fin - Fout) × 500
Or
Load (tons) = Flow (USgpm) × (Fin - Fout)/24
So, in case of Chillers and ΔT 10 F
GPM =(24/10 ) TR so that we say (GPM=2.4 TR )
in case of Cooling tower (Condensing Water)and ΔT 8 F :
GPM=3 TR
In case of District Cooling and ΔT 16 F:
GPM=1.5 TR
So please take care of these values before calculate load or flow.
16TH Tip:
How to calculate Diffuser Area
Q=A x V
Q---Flow Rate (cfm ,cubic feet per minute )
A---Area (Required, square feet)
V---Velocity -- (fpm , feet per minute)
for example, velocity 450 fpm in supply diffuser in an office with 1300 cfm , divided to two supply diffusers , so we
will have 650 cfm per diffuser with area (650/450=1.45 ft2 * 144 = 208 in2 )
Area for diffuser = 208 in2 ----- now we can select diffuser upon our requirements
-Square Diff. (14.42" x14.42" ) approx. we will use diffuser (15" x 15" )
it is neck size for diffuser
-Rectangular outlet. (width x depth - ex. 22"x10')
-Round Diff. (R=15 in)
it is a simple way to determine diffuser area.
Ref. ASHRAE Fundamentals Handbook
Ch. SPACE AIR DIFFUSION
17Th Tip:
As mentioned in previous tip (16th one) that will be about ( Air Distribution and all effective parameters (Noise ,
Throw , Furniture , vibration , applications..... )
*Air distribution systems affect not only indoor air quality (IAQ)
and thermal comfort, but also energy consumption over the entire
life of the project.*
that mean , we can make an accurate heat load but unproperly distributed air makes it uncomfortable and that
means losing the main purpose of air condition system , so lets abstract this in one of the most valuable guide
in this topic in my point of view , attached which is talking about:
1-All Definition about air distribution (throw , spread , drop ,.... ) and so on
2-Selection Fundamentals
3-Air Outlets types
4-Selection Procedures
5-special Designs
18Th Tip:
Room Air Distribution:
ASHRAE discuss this topic twice
1-ASHRAE HB Application , A57 Room Air Distribution
2-ASHRAE HB Fundamental , F20 Space Air Diffusion
Location for supply air outlet is more important than return intake ,
so we distribute supply at first then return ones.
Supply air outlet shouldn't be on front of sleeping person (so we make it on side of bed) , also not directly
above seating person (if we have an office for example) , or near doors and so on
for proper distribution but yourself in seating person shoes , where you feel comfortable it will be a suitable
location for supply air outlet.
19Th Tip:
Recommended velocities in supply and return air terminal.
Ref. ASHRAE HB HVAC Applications CH 57 and 48
20th Tip:
Some definitions
Diffuser : air terminal with deflecting blades which reduce air velocity to suitable level , on ceiling
Grill : Air terminal with multiple passages for air through, wall or ceilling
Slot Diffuser : Diffuser with one or several slots with an aspect ratio of 1:10 or more
Register : Combined grill and damper assemply (approx . 1 slot ,1 m lenght , from 80 to 100 CFM (50
l/s)(depending on face velocity used 80:100 fpm or 0.5 m/s )so if we have 2 slots 1.5 m lenght so flow range
will be about 300 cfm (about 140 l/s) )
Nozzel : an air terminal device designed to generate a low energy loss and thus produce a max. throw by min.
gravity
Spread : Max. width of the supply air terminal velocity
Coanda Effect : also called ceiling or wall effect , is the tendency of an air stream to follow a plane when the
stram is in contact with the plane this effect increase throw and reduce drop
21st Tip:
Noise and Vibration
One of the most important factors in many applications that must be taken into account (Residential , offices ,
Hospitals , Hotels ,...)
ASHRAE Recommended RC Values for different applications
Ref.:
ASHRAE HB HVAC Application , Ch48 (NOISE AND VIBRATION CONTROL)
22nd Tip:
Stack Effect
what is stack effect , stack Pressure , Stack effect proplems , Reverse stack effect...
simply ,it is a pressure difference happened due to temerature difference between outdoor and indoor and air
density.
in cold areas (outdoor temp. is lower than indoor )it is Stack Effect
it is Reverse Stack Effect if it gets warmer
(in our region and gulf areas )
Stack effect and Reverse Stack effect
in case of stack effect in cold climates air flows like a chimeny from lower levels to upper levels
in Reverse Stack Effect , air flows from upper levels down to lower levels
Ref. ASHRAE HB ,HVAC Applications Ch.04 Tall Building
Stack effect and Reverse Stack effect
in case of stack effect in cold climates air flows like a chimney from lower levels to upper levels
in Reverse Stack Effect , air flows from upper levels down to lower levels
Ref. ASHRAE HB ,HVAC Applications Ch.04 Tall Building
23rd Tip:
How Stack Effect and Reverse Stack Effect affect on building :
Stack effect causes problems more than Reverse stack effect specially in opening and closing doors and building
net pressure.
Ref.ASHRAE HB HVAC App. Ch.04 Tall Building
24th Tip:
Isolation Rooms
According to ASHRAE There are four types of Isolation Bedrooms depending on patient immunity and infection
degree
Ref. ASHRAE HVAC Design Manual for Hospitals and Clinics
Airborne Infection Isolation (AII)Room
Description as mentioned in the previous Tip.
Design Rules:
-Specially for patient have an airborne communicable disease.
-Designed to be negative pressure
-Exhaust air terminal to be above patient bed to prevent infection spread
-Supply air terminal to be near the door to protect staff
-Exhaust air directly to outdoor if mixed with other exhaust airflows , HEPA filters must be used.
simply: ‫المريض حامل لمرض معدي‬
Ref. ASHRAE HVAC design manual for Hospitals and Clinics
Protective Enviroment (PE) Room
In this case the patient is who must be protected against infectious microbials
Design Rules:
-For patients suffering from weakend immune and required protection
-Designed to be Positive pressure
-Exhaust air terminal near entrance door
-Supply air terminal above patient head
-Supply air terminal provided with HEPA Filter
Simply: ‫المريض مناعته ضعيفة‬
Ref. ASHRAE HVAC Design Manual for Hospitals and Clinics
25th Tip:
Isolation Room types Comparison
Ref.ASHRAE HvAC Design Manual for Hospitals and Clinics
Tip 26:
How to find climatic data for any country for calculation use ,
ASHRAE FUNDAMENTALS HANDBOOK
Chapter 14: CLIMATIC DESIGN INFORMATION
page 42(upon the version used)
Note:
Find the truth ,(Palestinian Territory, Occupied) it is an implicit acknowledgment of our right in land.
Tip 27:
Kitchen Ventilation part 1
Kitchen Different Duties and appliances :
How to specify kitchen duty (upon appliances used and Temperature if u have )
this is the first step to how to design Kitchen Ventilation.
Reference :ASHRAE Handbook Applications CH.33
Tip 28:
Kitchen Ventilation Part 2
it is a quick and simple method to calculate the minimum exhaust rate needed for a kitchen.
Note:
the table show the minimum exhaust rate that we can not be lower.
Reference:
ASHRAE Standard 62.1-2016
Tip 29:
Kitchen Ventilation Part 3:
different types of commercial kitchen hood and minimum exhaust rate for each one.
by this way we can calculate the value of hood fan capacity if we already have the hood in the kitchen.
Note: ‫ف مطابخ كبيرة بيكون موجود فيها شكل الهوود يعني بمعني تاني مفروشة فنقدر نحدد من شكل الهود نوعه وبالتالي هنحسب كمية الهواء المسحوب ودي‬
‫هتكون الطريقة االولي لو عندنا المطبخ مفروش‬.
Reference :
ASHRAE Handbook Application CH 33
Tip 30:
Commercial Kitchen Ventilation Part 4:
If the kitchen we deigned is not furnished (popular case) so we don't have neither Hood type nor area so Air Change
method is applicable .
by practice it is ranged between (30 to 50) ACH.
Q=AxV
CFM=((LxW) x H) kitchen volume) x ACH / 1.7
So, this method could be used to calculate unfurnished kitchen exhaust tie in.
in some cases we don’t even have kitchen area specially at echematic design stage as architect is not finished yet
so for example we have a restaurant without a specified kitchen area , i faces this case several time and used to
take 30% of whole restaurant area as kitchen.
Note : 15 ACH is recommended only in case of ceiling fan for kitchen ventilation.
‫ ولكن ده‬15 ‫الهواء‬. ‫ببساطه لو بعمل تهويه للمطبخ والمروحه مش فوق منطقه الطهي بيكون معدل تغيير‬
‫مبيكونش كافي ف باقي الحاالت‬.
Reference :
ASHRAE Handbook Application CH 33
DW 172-2018
Tip 31:
Residential Kitchen Exhaust Rate:
as shown in table we use lower value 25 lps (litter per second, L/s) in case of continuous system if not we use the
highest one.
simply , in case of using Recovery Unit in ventilation system (continuous) exhaust rate will be 25 lps , if the system is
more simple using (single axial (wall mounted) fan , inline small fan) take it 50 lps.
for continuous ventilation we use 5 ACH.
‫ببساطه بنستخدم القيمه الاقل في حاله المشاريع الكبيره اللي بنلجأ فيها لاستخدام ال‬
Recovery Unit
‫طبعا لان كميه الهواء المسحوب بتكون كبيره ولتوفير الطاقه وكفاءة النظام والدقه‬
‫اما في حالة المشاريع السكنيه الاصغر او المباني السكنيه الخاصة واللي بيكون النظام فيها ابسط بنستخدم القيمه الاعلي‬
Note:
Notes after every table is very important.
Ref.:
ASHRAE Standard 62.1
ASHRAE Standard 62.2
Tip 32:
Hood Types
Type I :
Type II
ASHRAE defined it clearly.
Ref:
1. ASHRAE Standard 154
Ventilation for Commercial Cooking Operations
2.ASHRAE Handbook - HVAC Applications CH.33
Tip 33:
Hood Type II :
Hood requirement check table 2 in same Ref .
Hood Sizing , hood overhanging , min. exhaust rate ,
Ref. : ASHRAE Standard 154 (Ventilation for Commercial Cooking Operations)
Tip 34:
Makeup air for Kitchen
after calculate Hood Exhaust air rate (by any method) either linear meter or ACH , the next step is to calculate
makeup air for it
Q(Fresh Air) = 0.8 : 95 X Q (Exhaust Air)
Different Type of replacement air
Supply air , replacement air , makeup air and transfer air , difference between them will lead us to next tip (Air
‫)‪Balance for kitchen‬‬
‫ببساطه هل تعويض الهواء ده هيكون عن طريق نظام تهويه او عن طريق نظام التكييف او عن طريق انتقال الهواء من مكان الي‬
‫مكان داخل المبني‬
‫‪Ref. :‬‬
‫‪1.ASHRAE Standard 90.1‬‬
‫‪2.ASHRAE Standard 154‬‬
Tip 35:
Kitchen Air Balance :
in both methods dinning room is positive pressure (air transfer from dinning to kitchen) so noting moves from
kitchen to dinning ( smell , smoke ,... and so on) , on opposite kitchen is negative for the dinning.
‫ببساطه المطبخ ضغطه بيكون اقل من غرف الطعام المفتو ح عليه علشان مفيش اي‬
(‫) روائح او دخان او غازات وتقليل ضوضاء وهكذا‬
‫وممكن نقول ان هو ده مبدأ توازن الهواء شوف انت عايز الهواء يمشي اتجاهه ازاي وبالتالي هتظبط ضغط المكان (المقصود بيه‬
) ‫كميه الهواء‬
Ref. :
ASHRAE Standard 154
Tip 36:
Kitchen Ventilation, Ecology Unit
or Pollution Control Unit (PCU ). It is a multi stage filtration system designed to remove smoke , grease particles and
to control odor from the exhaust air from kitchen along with exhaust fans , it is considered a perfect solution for
commercial kitchens serve Hotels, restaurants, Hospital and Food industry.
Ecology units are designed as per NFPA 96 standard.
Ecology units components including Electrostatic precipitator (ESP) ,Filter section, Odor control section, Fan section
and Control panel and optional stage of HEPA filter.
It should regularly cleaned and maintained.
‫ عباره عن مروحه سحب مع عده مراحل من الفلاتر‬Ecology Unit ‫ببساطه ال‬
Ref.:
NFPA 96 (Standard for Ventilation Control and Fire Protection of commercial Cooking Operation
‫‪Tip 37:‬‬
‫‪Kitchen ventilation‬‬
‫‪Kitchen Pressure differential:‬‬
‫‪how to decide even this kitchen will be under negative or positive pressure.‬‬
‫‪simply , it is depend on where is that kitchen , opened to a dinning room or separately based in outdoor.‬‬
‫ببساطه لو المطبخ ده مفتوح ع ‪ Dinning room‬يبقي ضغط المطبخ اقل منها‬
‫علشان الدخان والروائح متتنقلش من المطبخ للغرفه‬
‫اما لو المطبخ ده مبني قائم لوحده (زي عربيات الاكل ف الشارع (‬
‫ف الحاله دي بيكون المطبخ ضغطه موجب بحيث حركه الهواء تكون من جوه المطبخ للخارج علشان مينتقلش الهواء الملوث‬
‫والاتربه لداخل المطبخ‬
‫ولو المطبخ ده ف اماكن مفتوحه ع بعض زي اماكن الاكل ف المولات الكبيره بيكون ضغط الهواء سالب بالنسبه للاماكن اللي‬
‫حواليها‬
‫‪.‬بببساطه اكتر انا محتاج الهواء يتحرك ازاي بالتالي هقدر احدد الضغط موجب او سالب‬
‫‪Ref.:‬‬
‫)‪ASHRAE Standard 154 (Ventilation for commercial cooking operation‬‬
Tip 38:
Kitchen Duct System :
duct type , duct construction and installation.
Ref.:
ASHRAE Standard 154 (Ventilation for Commercial Cooking Operations)
Tip 39:
Duct Air Flow: velocity limitation in kitchen exhaust duct.
Ref.: ASHRAE Standard 154 (Ventilation for Commercial Cooking Operations)
Tip 40:
Exhaust Duct Test Method:
Ref.:
ASHRAE Standard 154 (Ventilation for Commercial Cooking Operations )
Tip 41:
Minimum Exhaust Rate:
on of most important table for HVAC daily use , simple and valuable.
to get min. exhaust rate for places to get exhaust air from, whether using space area or per unit.
for toilets , residential kitchen and shower room it is calculated L/s for unit , that means for example for whole res.
kitchen exhaust rate will be 50 L/s , if we talk about trash room then calculate its area then multiply by 5.0 L/s (if we
have a trash room with 20 sq.m then ventilation rate will be 100 l/s ) as min. exhaust rate.
Note:
for continuous system we use lower value of exhaust otherwise we us the highest one.
ASHRAE notes below any table is very important.
Ref.
ASHRAE Standard 62.1 (ventilation for acceptable indoor air quality )
Tip 42 :
Minimum Ventilation Rate.
for almost all applications , table 6.2.2.1 in ashrae standard mentions min. ventilation rate (fresh air required for
any place)
fresh air for any place is divided to two parts ,'
1. Fresh air required for space area
2. Fresh air required for people in that place (no. of people calculated from same table)
for example : Office space with 120 sq.m
FA for area = 120*0.3=36 l/s
No. of people (table mentioned that for every 100 sq.m there are 5 person ) so, for 120 sq.m we have 6 person
then
FA for each person = 6*2.5 = 15 l/s
so, total min. ventilation rate required for this space =36+15=51 l/s
And so on
(Notes below table )
Ref:
ASHRAE 62.1 (Ventilation for acceptable indoor air quality)
Tip 43:
Air Balance for sample residential Flat :
It is a simple sample for air balance in single flat in a residential building using Recovery Air units (continuous
system) in fresh air system.
whole flat is positive corresponding to corridor ,
this is the sequence used in this sample to calculate fresh air
1- get exhaust rates for places need air to be exhausted from (kitchen and toilets , store , garbage if founded) then
2- calculate fresh air required for occupied spaces as ASHRAE Standard 62.1(tip 42)
3-for places need to be positive compare between air exhausted rate and fresh air rate ,simply if we calculate fresh
air (by ashrae table ) needed for master bedroom it will be 10 l/s then it will be negative for toilets so in this case
(exhaust is more than fresh air ) we increase fresh air to be 10 : 15 % more than exhaust air so you will find it as 15
l/s
while calculating fresh air using excel sheet we calculate fresh air by both method , compare between them and take
the highest value.
all of that is to maintain positive and negative pressure as shown.
also for living room it have both toilet and kitchen so fresh air should be more than exhaust value for them together.
whole flat needed to be positive pressure so the whole building will be positive also.
‫ لكل من الحمامات والمطابخ ولو ف مخازن‬exhaust air ‫ احنا بنشوف قيم ال‬: ‫ببساطه‬
‫او غرف نظافه او اي اماكن محتاجه طرد الهواء وبعدين نحسب الهواء الفريش من اشري ونقارن قيم الهواء الفريش والمطرود بيحث نحافظ علي ضغط‬
‫المكان واتجاه الهواء داخل المكان‬
‫ ونعتبر ده هو قيمه الهواء الفريش المطلوب للمكان الن المكان‬% 15: 10 ‫ولو لقينا ان الفريش اقل من الهواء المطرود بالتالي نزود قيمه هواء الطرد بنسبه‬
‫ الزم يكون‬.
.‫ضغطه موجب وبالتالي المبني كله يكون ضغطه موجب‬
‫ هنالقي انها مفتوح عليها المطبخ والحمام وبالتالي بنجمع‬living room ‫ف حاله ال‬
‫الهواء المطرود منهم لحساب الهواء الفريش المطلوب للمكان وكذلك بالنسبه الي مكان غيره‬.
Ref.:
ASHRAE Standard 62.1 (Ventilation for acceptable indoor air quality )
Tip 44:
Design Criteria for Office building
Design Criteria are different from one application to another and
that is mentioned in ASHRAE for various applications like:
Commercial and public buildings , Hotels and motels and Educational facilities
design criteria (indoor temperature, Relative Humidity , noise level , ventilation rates ,....)
we can find also , system recommendations upon building area.
attached if Design Criteria and system recommendation for Commercial and public building application.
these values may be different from other ASHRAE standard but it is recommended for a specific application.
Ref.:
ASHRAE handbook for HVAC Application
Tip 45:
Design Criteria for Hotel , Motel and dormitories
Ref.:
ASHRAE Handbook - HVAC Application
Tip 46:
Design Criteria and HVAC system recommendations for educational Facilities:
Ref.:
ASHRAE Handbook - HVAC Applications
Tip 47:
Design Criteria(Temperature , relative humidity and specific filtration requirements) for industrial facilities.
-Air Conditioning design is not only to provide comfortable environment , but also a necessary for various industries
to complete production process to obtain certain (temperature , humidity and filtration req.).
-in some industrial facilities it is very important to have after production filtration process to remove airborne
contaminates such as manufacturing plants , laboratories and nuclear power plants.
-building environment should be healthy and comfortable for workers.
-Energy could be saved by proper use of insulation and ventilation , and by recovery of waste heat in industrial
buildings which require large quantities of energy.
Note :
photos attached for example but not limited to , Ref. has many and common industrial applications.
Ref.:
ASHRAE Handbook - HVAC Applications Ch.14 (Industrial Air Conditioning)
Tip 48:
Lighting power density
one of important parameters in heating and cooling load calculations is lighting density and HAP
Ref.:
ASHRAE Handbook-Fundamentals F18
ASHRAE Pocket Guide for Air Conditioning ,Heating ,Ventilation ,Refrigeration Ed.09
Tip 49:
Cooling load check figure
it is a primary method to check calculation but we can not depend on it for final calculation result.
Note :
this table was removed from next edition of the reference (09th edition) so it is a proof of not supporting this
table for final Result.
Ref.:
ASHRAE Pocket Guide for Air Conditioning , Heating , Ventilation , Refrigeration 8th edition.
Tip 50:
Fire and Smoke Dampers installation
it is important to know when and which damper to install while penetration.
the figure attached show almost all cases we face while design AC duct.
Ref.:
NFPA 90A (Installation of Air Conditioning and Ventilation Systems )
Tip 51:
Smoke Damper
Smoke damper function in case of smoke management and smoke control
Ref.:
ASHRAE Handbook - HVAC Applications Ch.53 (Fire and Smoke Management)
Tip 52:
Dampers Definitions
Ref.: NFPA 90A (Installation of Air Conditioning and Ventilation Systems)
Tip 53:
Damper Control
Ref.: NFPA 90A 90A (Installation of Air Conditioning and Ventilation Systems)
Tip 54:
Fire Damper Location
Ref.: NFPA 90A (Installation of Air Conditioning and Ventilation Systems)
Tip 55:
Stair Pressurization system
there are two types of system depending on building height
single injection system and multi injection system
Ref.: ASHRAE HANDBOOK - HVAC Applications Ch.53