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4  FM quick reads on HVAC

1. Why Some Geothermal Systems Will Save More Than Others


Geothermal heat pump systems promise to provide lower cost heating and cooling than conventional systems, with far less reliance on fossil fuels. But the amount of savings varies from system to system. To understand why, there are a couple of points facility executives should keep in mind.

One important point to remember is that geothermal systems offer more savings in cooling-dominated climates. But if the load between heating and cooling is balanced, geothermal systems can also operate cost effectively.

Another important point: The greater the temperature difference between the air and the ground, the more efficient the system.

A final efficiency consideration: With large systems, very warm ground temperatures — for example, on a hot day in late summer — may make it necessary to dissipate some heat in a fountain or other open water source or to use it for domestic purposes.


2.  Understanding Bioterrorism: Solutions for Facilities

This is Chris Matt, Associate Editor of Maintenance Solutions magazine. Today’s tip is better understanding the threat of bioterrorism attacks.

Besides learning about the most common biological agents, managers also must understand the most likely mechanisms terrorists could use in an attack. Four methods are the most likely. Each will require a different response to protect building occupants. The response also will vary with the type of building and the type of HVAC systems serving that building.

The first type of incident involves an indirect attack. In this scenario, a large-scale release of a biological agent occurs outside a facility. If the facility is downwind from the release, a portion of the biological agent could enter the building through outdoor-air intakes for the HVAC system.

A second type of incident is the release of the biological agent directly into the HVAC system outdoor-air intakes. The biological agent enters the system and is distributed to areas of the building that system serves. How widely the agent is spread will depend on the system’s design and how much of the building the system serves.

A third possible scenario is similar to the second, only the agent is released within the building itself, directly into the return-air portion of the HVAC system. Again, the distribution of the agent depends on the design of the HVAC system.

The fourth scenario involves the release of a biological agent within a specific area, such as a conference room, lobby, or classroom. While much of the release would be confined to that space, the biological agent can spread readily through the building’s HVAC system or even as people move from one area in the building to another.

3.  Why Some Geothermal Systems Will Save More Than Others

Geothermal heat pump systems promise to provide lower cost heating and cooling than conventional systems, with far less reliance on fossil fuels. But the amount of savings varies from system to system. To understand why, there are a couple of points facility executives should keep in mind.

One important point to remember is that geothermal systems offer more savings in cooling-dominated climates. But if the load between heating and cooling is balanced, geothermal systems can also operate cost effectively.

Another important point: The greater the temperature difference between the air and the ground, the more efficient the system.

A final efficiency consideration: With large systems, very warm ground temperatures — for example, on a hot day in late summer — may make it necessary to dissipate some heat in a fountain or other open water source or to use it for domestic purposes.

4.  Fans May Offer Surprising Energy Savings

It’s no secret that HVAC systems account for a significant percentage of the energy used by a building. But it’s not only the heating and cooling systems that present opportunities for big savings.

Facility executives should also take a close look at the fan systems in a building. In doing so, however, facility executives should understand how the energy consumption of a fan varies with its speed.

The amount of power used by a fan is proportional to the cube of the speed of the fan. That’s counterintuitive. Chillers, for example, use less energy to produce a ton of cooling at full load than at part load. Fans are just the opposite. At full speed, they are at their least efficient. That means even a small reduction in fan speed can produce surprising energy savings.

One option for cutting fan speeds is to install variable frequency drives on fan motors. That way, fans can be slowed down when conditions in the building don’t require them to operate at full speed.


RELATED CONTENT:


HVAC , Geothermal Systems , Energy , Green

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