HVAC
An inventory of your hospital’s HVAC system will help you measure its potential environmental impact and benchmark it against other types of systems. If you already possess an intimate knowledge of your hospital’s HVAC system, this will be familiar information to you. If, however, you are not an infrastructure expert or systems engineer, you will need this basic knowledge of HVAC systems in order to properly establish the baselines you’ll need for your program.
Typically, the HVAC System consumes between 40-60% of the energy consumed by the facility (1). In the facility evaluation section below there are examples of the various types of HVAC systems that can exist in any building. You can use these system examples as a general guide to help you clarify what the primary HVAC system is and all of its components. From there you can also count all supplementary components within the building so that you can account for all the components. Learn more.
HVAC
All HVAC systems in current use fall into one of four categories. Those categories are Air-to-Air, Air-to-Water, Water-to-Water, and Water-to-Air. Each has its own unique architecture and set of system components which are listed below.
Design Schematics for each type of system and it’s various components can be found below under “Documents”
Air-to-Air
Air-to-air systems work by absorbing heat from the air in one space and transferring it to another. These systems are typically referred to as “unitary direct expansion” or “unitary DX” for the way the system is often contained in a single large unit, usually on the roof (there are also so-called “split DX” systems). See diagrams.
Common system components:
Rooftop Unit
Split DX
Air Source VRF
Make-Up Air Unit (DOAS)
Ventilation Fans
Auxiliary Split AC Systems
Unit Heaters (Electric)
VAV Boxes
Air-to-Water
Also called “air source heat pumps”, air-to-water systems absorb heat from the outside air and transfer it to water, converting it into usable hot water (and cold air). The water is then circulated through the building via radiators or underfloor heating. See diagrams.
Common system components:
Self-Contained AC Units
Make-Up Air Unit
Cooling Tower
Ventilation Fans / H&V Unit
Boiler (Hot Water/Steam/Gas)
Fin Tube radiation
Unit Heaters
Electric Baseboard
VAV Boxes
Domestic Hot water system
Water-to-Water
A water-to-water heat pump transfers heat between two water flows (a source and a sink). Heat is absorbed from a hot water source to create chilled water. Heating is produced by circulating hot water through the building through baseboard heaters, or radiant floor heating. See diagrams.
Common system components:
Air Handling Unit
Fan Coils
Make-Up Air/Ventilation Unit
Cooling Tower
Ventilation Fans
Auxiliary Split/Packaged DX Systems
Pumps
Boiler (Hot Water/Steam/Gas)
Fin Tube radiation
Unit Heaters
VAV Boxes
Electric Baseboard Heat
Domestic Hot water system
Water-to-Air
Water-to-air heat pumps absorb heat from hot water to create chilled water and also hot air (which is distributed through a building via ductwork). See diagrams.
Common system components:
Air Handling Unit
Fan Coils
Make-Up Air/Ventilation Unit
Indoor Split Chillers
Ventilation Fans
Auxiliary Split/Packaged DX Systems
Pumps
Boiler (Hot Water/Steam/Gas)
Fin Tube radiation
Unit Heaters
VAV Boxes
Electric Baseboard Heat
Domestic Hot water system
(1) U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, Integrating Health & Efficiency in Healthcare Facilities, June 2021