Through the Energy & Climate Projects Series, we will be introducing key projects from Sheridan’s campus-wide energy saving initiatives as implemented by the Integrated Energy and Climate Master Plan (IECMP). In last week’s installment, we began introducing the importance of the ever-evolving HVAC system as part of the BAS Replacement and Mechanical Upgrades project. This week we will focus on breaking down a basic HVAC system.
HVAC System Goals
The HVAC is necessary in maintaining good air quality as it is essential in occupant comfort, health, and productivity. All HVAC systems have similar goals in terms of maintaining occupant comfort with energy efficiency in mind. These goals are aimed at maintaining:
- Temperature control
- Fresh air supply
- Air filtration
- Humidity control
- Discreet and quiet operation
Both commercial and residential HVAC systems heat or cool by supplying air through the ductwork but differ in their ability to heat or cool rooms on an individual or simultaneous basis. In a residential building, a single thermostat controls the entire system but unfortunately such a system can’t take into account temperature variation in any other room. Sheridan faces a similar issue in that many of its zones are independently controlled and there’s no way for the dated HVAC system to collectively manage the zones and optimize overall building system. The recent HVAC upgrades and thermostat installations will allow occupants in multiple zones to have their unique preferences met at the same time and permits the system to optimize for energy and comfort.
A Basic HVAC System
Each office or classroom space has different needs for heating cooling due to varying conditions such as number of people and equipment. These needs (or loads) from occupants, equipment, and weather place a demand on the HVAC system. A basic HVAC system includes a supply fan, return fan, heating and cooling coils, filters, dampers, sensors, and a humidifier.
The diagram above illustrates an HVAC system supplying conditioned air for single or multiple zones. Air is circulated through primary heating and cooling equipment in order for energy transfer to occur. In other words, the heating and cooling coils will change the temperature of the air depending on the temperature demand. Fans within the air handling unit are used to circulate air through various components and force it through the ductwork. Air flow from the ductwork enters occupied spaces through grills or diffusers which distribute air evenly and efficiently.
A continuous supply of fresh air (about 10-20%) is required to reduce the build of CO2 and other air contaminants. Dampers in the air handling unit select the mix of fresh outdoor air and air returning from the spaces to be recirculated into the building. Consisting of one or more blades, dampers can be controlled by a digital, pneumatic, or electrical actuator.
Humidity affects how occupants perceive comfort. High humidity levels require colder temperatures for occupants to be comfortable. High humidity levels are controlled by cooling air below the dew point using the cooling coil so that the water condenses. Low humidity levels are mitigated by addition of humidity into the air by the humidifier.
Because recirculated and outdoor air contain a variety of contaminants (e.g. particulates, dust, vehicle exhaust), banks of filters are used to capture contaminants before the supply air enters the building.
Sheridan’s HVAC System
A major focus of the IECMP is to modernize Sheridan’s HVAC system with energy efficiency in mind. Continue following our series to learn about how Sheridan is improving a basic HVAC system using innovative technologies. We will be highlighting building and zoning control upgrades, the new building automation system (BAS), and the customized digital thermostats and sensors.
Energy Manager of the OfS Herbert Sinnock stated that the team welcomes feedback from the Sheridan Community with regards to the new HVAC system and other ongoing projects. By providing your feedback on comfort levels, we can direct our efforts to improve system operations. Send us your feedback at constructionfeedback@sheridancollege.ca.