# Presentation: 517946

## HVAC 101

- The Basics of Heating, Ventilation and Air Conditioning
- Presented by:  Mike Barcik and Jeff Ross-Bain, PE
- Southface Energy Institute

## Southface Energy InstituteSensible Solutions for Environmental Living

*Energy Code Workshops*
*Greenprints*
*Commercial Systems*
*EarthCraft House*

*www.southface.org*

## HVAC	

- Heating, Ventilation and Air Conditioning
- Provides _*comfort*__ _for people
- Allows humans to _*exist*_ under adverse conditions.

## Comfort

- Comfort is primary intent of HVAC systems.
- Productivity
- Building Durability
- Health
- Mold

## Load Calculations

- Heating and Cooling
- Accuracy *important!*
- Design conditions
- Building shell load
- R, U value
- Internal load
- Ventilation load
- Infiltration
- Occupancy schedules

## Heat Transfer

- Conduction
- Convection
- Radiation
- Resistance (R-Value)
- U = 1 / R
- Q = U x A x T

- U-Value is the rate of heat flow in Btu/h through a one ft2 area when one side is 1oF warmer

## Solar Heat Gain Coefficient

**The amount of solar heat energy allowed to pass through a window**
**Example:  SHGC = 0.40**
**Allows 40% through and turns 60% away**

**Notes:**
Solar Heat Gain Coefficient (SHGC)
The glazing’s effectiveness in rejecting solar heat gain.
Part of a system for rating window performance used by the National Fenestration Rating Council (NFRC)
Gradually replacing shading coefficient (SC) in product literature and design standards convert SC to SHGC by multiplying the SC value by 0.87

## Psychrometrics

- Dry bulb temp.
- Wet bulb temp.
- Humidity
- Dew point
- Moisture content
- Heating
- Cooling
- Humidify
- De-Humidify

- _Psychrometric Chart_

## Basic Refrigeration Cycle

- Expansion Valve

- Compressor

- Evaporator

- Condenser

## Basic HVAC Equipment

- Fans / Blowers
- Furnace / Heating unit
- Filters
- Compressor
- Condensing units
- Evaporator (cooling coil)
- Control System
- Air Distribution System

## Slide 11

## System Types and Common Terms	

- Packaged Rooftop Unit
- Split System
- Heat Pump
- Geothermal
- Air to Air
- Hydronic (water)
- PTAC / PTHP

- Constant Volume
- Variable Volume
- Indoor Air Quality
- Direct Expansion

## Packaged Rooftop Units

## Split System

- <date/time>

- FURNACE

- A/C UNIT

- Ductwork

- Heating
- and Cooling
- Equipment

- Temperature &
- Humidity Controls

**Notes:**
An HVAC system consists of a 
heating and/or cooling source, 
a distribution system (e.g. ductwork or hot/chilled water piping) and 
temperature controls.

## Heat Pump

- Operate on simple refrigeration cycle
- Reversing the cycle provides heating
- Temperature limitations
- Air to air
- Water source
- Geothermal
- Lake coupled

## Geothermal Heat Pump Systems

## Variable Air Volume

- T

- T

**Variable Speed Return Fan**

**Return Air**

**Return Ducts**

**Zone Thermostat**

**Reheat Coil**

**VAV Box**

**Supply Ducts**

**Variable Speed Supply Fan**

**Filters**

**Cool Coil w/Temp Reset**

**Heat Coil w/Temp Reset**

***HVAC-***

## Terminal Units

- Variable volume:  Parallel

- Constant volume:  Series

## Hydronic systems

- Pumps
- Piping
- Valves

## Control Devices

- Thermostats
- Manual
- Programmable
- Optimum Start
- DDC Systems
- Variable Speed Drives
- Automatic Valves and Dampers
- Outdoor Sensors

## Major Equipment

- Chillers
- Boilers
- Cooling Towers

## Economizers

- Air Side

- Water Side

## Economizers

- Free cooling source:  When available, use cool outdoor air instead of mechanically cooled air.

**55 ****o****F**

**80 ****o****F**

**Minimum supply of outside air**

**Normal Operation**
**Outside air dampers are positioned to provide the minimum outside air**

**Economizer Operation**
**Outside air dampers are fully open.  Maximum outside air is provided**

**80 ****o****F**

**55 ****o****F and up**

**85%**
**outside air**

**85%**
**exhaust**

***HVAC-***

## Zoning and Economizers

- Economizers provide “free cooling”   when outdoor conditions are optimal
- Proper orientation & zoning yields comfort & efficiency

***HVAC-***

## Air Distribution	

- Ductwork
- Metal
- Flexible
- Ductboard
- Grilles, Louvers,
- 	  & Registers
- Dampers
- Shut off
- Fire
- Smoke
- Sealants
- Supports

## Return Plenum Problems

***HVAC-***

## Additional Equipment

- Energy Recovery Units
- Desiccant Systems

## Additional Equipment

- Heat Exchangers
- Humidifiers
- Silencers

## Mechanical Dehumidification

- Return air is mixed with ventilation air
- Cold coil condenses moisture
- Heat is added back (electric or gas) so that room air is not over cooled- *Reheat*

- Filter

## Historical Minimum Ventilation Rates (cfm/person)

- Tredgold 1836

- Nightengale 1865

- Billings 1895

- Flugge 1905

- Yaglou 1938

- ASHRAE 62-73

- ASHRAE 62-81

- Smoking 62-81

- ASH- RAE 62-89

- Smoking 62-89

## Improved Ventilation Effectiveness

- Mechanically provide filtered and dehumidified outdoor air to the breathing space
- Vary ventilation based on the number of occupants and process loads - changes in occupancy can be measured by CO2 sensors
- Consider designs that separate ventilation and space conditioning
- Utilize heat recovery systems to reduce system size and ventilation energy costs

## Improved Ventilation Effectiveness

- Effective mixing of ventilation air within space
- Net positive pressure in the southeast; exhaust from appropriate spaces
- Provide clean outdoor air, avoid:
-  loading docks
-  exhaust vents
-  plumbing stacks
-  waste collection
-  stagnant water

## Additional Information / Resources

- ASHRAE – The American Society of Heating, Refrigerating and Air-Conditioning Engineers
- www.ashrae.org
- Southface Energy Institute  www.southface.org
- Geothermal heat pump consortium www.geoexchange.org
- www.buildingscience.com
- www.energycodes.gov