Air Filters Efficiency Classification

ASHRAE 52.2: Filter testing was originated from America in 1930 (ASHVE and AFI code). It was then reviewed and modified in 1967 and 1968. ASRHAE collaborated with American National Standard Institude (ANSI) in 1992 to create ASHRAE-ANSI 52.1. Finally updated to ASHRAE 52.2 in 2007.

Psychrometric Programming Functions

ibrary of psychrometric functions to calculate thermodynamic properties of air for Python, C, C#, Fortran, JavaScript and VBA/Excel

Lighting Rules Of Thumb (HVAC)

Using lighting rules of thumb for final design of HVAC and lighting.

Constant Volume Air Handling

Shows the general arrangement for the four-channel control of an air handling system serving one zone in which the four channels control, in sequence, heating → heat recovery → fresh air (‘free’ cooling) → chilled water-based cooling.

Solar Rotation

Solar rotation is able to vary with latitude because the Sun is composed of a gaseous plasma. The rate of rotation is observed to be fastest at the equator (latitude φ=0 deg), and to decrease as latitude increases. The differential rotation rate is usually described by the equation shown.

Thermodynamic Properties (R407A)

Thermodynamic Properties (R407A)

Thermodynamic Properties (R134A)

Thermodynamic Properties (R134A)

Thermodynamic Properties (R123)

Thermodynamic Properties (R123)

Thermodynamic Properties (R11)

Thermodynamic Properties (R11)

Refrigerants Data Summary

An updated table for Refrigerants Data.

Infiltration Rules Of Thumb

The infiltration rate is the volumetric flow rate of outside air into a building, typically in cubic feet per minute (CFM) or liters per second (LPS). The air exchange rate, (I), is the number of interior volume air changes that occur per hour, and has units of 1/h.

Trace 700 Software

TRACE 700 enables building designers to optimize the building, system and equipment designs on the basis of energy utilization and life-cycle cost. The Trane software for TRACE 700 facilitates analysis of the energy and economic effects of virtually any chiller plant configuration by allowing users to manipulate a wide range of variables and create a profile of their specific building.

Carrier Hap Software

Carrier’s Hourly Analysis Program is two powerful tools in one package – versatile features for designing HVAC systems for commercial buildings AND powerful energy analysis capabilities for comparing energy consumption and operating costs of design alternatives.

Cooling Load Calculation Procedure

Cooling Load Calculation Procedure for HVAC Design. From Obtain Building Characteristics to Outdoor Design Weather Conditions and indoor design temperature to be maintained in each space.

Cooling Load Rules Of Thumb

Cooling Load Rules Of Thumb for HVAC design of Banks, Court Houses, Municipal Buildings, Town Halls, Police Stations, Fire Stations, Post Offices, Precision Manufacturing, Computer Rooms, Restaurants, Kitchens (Depends Primarily on Kitchen Equipment), Cocktail Lounges, Bars, Taverns, Clubhouses, Nightclubs, Hospital Patient Rooms, Nursing Home Patient Rooms Buildings w/100 percent OA Systems (e.g., Laboratories, Hospitals) Medical/Dental Centers, Clinics, and Offices Residential Apartments (Eff., One-Room, Two-Room) Motel and Hotel Public Spaces Motel and Hotel Guest Rooms, Dormitories School Classrooms Dining Halls, Lunch Rooms, Cafeterias, Luncheonettes Libraries, Museums Retail, Department Stores Drug, Shoe, Dress, Jewelry, Beauty, Barber, and Other Shops Supermarkets Malls, Shopping Centers Jails Auditoriums, Theaters Churches Bowling Alleys

Indoor Design Conditions

Indoor design conditions for HVAC design of Office Buildings, Commercial Facilities
General Spaces, Educational Facilities, Food and Beverage Service, Hotels, Motels, Resorts, and Dormitories, Correctional Facilities, Retail Stores and Specialty Shops
Theaters, Sports and Entertainment, Transportation, Storage Facilities, Workrooms, Private Dwelling—Single and Multiple, Laboratories, Computer Facilities, High-Tech Industrial, Special Facilities, Hospital Nursing Units
Obstetrical Facilities, Emergency, Surgery, and Critical Care, Hospital Facility Support Areas, Diagnostic and Treatment Areas, Hospital Service Areas
Sterilizing and Supply…

Induction (Air/Water) System

Perimeter induction units – usually located under windows – blend primary air from the air-processing unit with secondary air from within the room. The high-velocity processed air delivery is induced into the unit through restrictive nozzles.

Fancoil (Air/Water) Unit And Induction Diffuser

An alternative discharge unit for application to the induction system shown on the previous page. Instead of nozzle injection of air, a low-powered fan is used to disperse a mixture of primary and secondary air after reheating or cooling from an energy exchanger within the unit.

Chilled Beams And Ceilings

Chilled beams and chilled ceilings require a relatively modest cooling water temperature (14–17°C), which can be obtained using natural cold water storage or free cooling from outside air over periods of the year depending on climate.

Dual Duct System

The dual duct system is another means of providing varying air temperatures to different rooms in the same building. There is no water circulation to peripheral discharge units with terminal reheaters or coolers. This simplifies the plumbing installation as heating and cooling elements for each duct are located in the plant room. However, the system is space consuming and adequate provision must be made in suspended ceilings or raised flooring to accommodate both distribution ducts. The system is most energy economic when heating and cooling elements operate individually.

Variable Air Volume (VAV)

The VAV system has a central air-processing unit to produce air at a specified temperature and relative humidity. The conditioned air from the main unit is conveyed in ductwork to ceiling diffusers which incorporate thermostatically controlled actuators. These can change the air volume to suit each room load. In a large room, several of these VAV ceiling units may be controlled by one room thermostat.


Depending on the state of the air on entering a spray washer, it can be humidified or dehumidified. Humidification in the presence of moisture is understandable, but dehumidification is less easy to comprehend. It occurs when the spray is at a lower temperature than the air and the dew point of the air.

Data Centers Cooling Systems

In a data center, the HVAC system energy consumption is dependent on three main factors: outdoor conditions (temperature and humidity), the use of economization strategies, and the primary type of cooling consider the following:

Flexible Duct Calculator

Flexible Duct Calculator based on four different methods. Based on Friction Loss, Based on Duct Diameter, Equivalent Rectangular Duct, Equivalent Round Duct Diameter. Also table of Maximum Recommended Supply Velocity.

Air Change Cfm Calculator

The rate at which air is exchanged (in the premises) represents another method of measuring ventilation capacity & effectiveness. Air exchange rate is typically expressed in Air Changes per Hour – “ACH”. Air changes per hour can be estimated by determining the total air supplied to, and removed from, the premises “total air exchange” or the outdoor (fresh) air supplied to, and removed from, the premises “outdoor air exchange”.

Air Conditioner Btu Calculator

This calculator is used to determine the capacity of room Air Conditioner. An air conditioner is a system or a machine that treats air in a defined, usually enclosed area via a refrigeration cycle in which warm air is removed and replaced with cooler air.

Solar Geometric Angles

Solar Geometric Angles are all critical to the calculation of solar energy on any given surface at some orientation. To calculate the energy balance across any time scale with respect to the incident solar radiation, you must know the geometric relationships that define the spherical realities of planetary motion relative to the sun for specific tilted surfaces on the planet.

Interactive Psychrometric Chart

The aim of this web app is to create an interactive psychrometric chart on which you can project a range of comfort metrics as well as mapping weather data or room air conditions calculated using EnergyPlus. You can add or remove lines for a range of different metrics or highlight them individually to assist with dynamic explanations or presentations.

Hvac Load Calculations

The accurate calculation of heating and cooling loads is essential to provide a sound bridge between fundamental building design decisions and an operating building. If loads are substantially underestimated, occupants and users will likely be hot or cold. If loads are substantially overestimated, equipment will be oversize (usually wasting money, reducing efficiency, increasing energy consumption, and often imperiling comfort).