4  FM quick reads on Energy Efficiency

1. Ground Source Heat Pumps Harness Earth Energy


Today’s tip is about ground source heat pumps, also known as geothermal heat pumps, which, when incorporated into the design of a new building, can trim a facility’s energy bill compared to buildings heated and cooled with traditional systems.

Ground source heat pumps harness the energy of the Earth – geothermal heat – to provide cheap, efficient cooling in the summer and heating in the winter. Because their initial expense is significantly greater than traditional HVAC, they have a payback period from 5 to 12 years, in most cases. But they can save as much as 60 percent on energy costs compared with a traditional HVAC system and the payback period shortens as energy costs continue to rise.

The most critical factor in determining whether a geothermal heat pump system is cost effective is the load. If there is a good balance between heating and cooling, the systems can operate cost effectively. A more cooling-dominated building can see even greater energy-cost savings.

There is two general categories of ground source heat pumps: Open loop and closed loop. Open loop systems are less common, usually deriving their energy from ground water sources. Closed loop systems are comprised of a continuous loop of vertical or horizontal pipes placed in the ground with a liquid circulating through them. In vertical closed-loop systems, holes of 300 feet or more are drilled into the earth.

Because geothermal heat pumps use renewable energy, some utilities or third-party organizations may offer incentives or rebates to help defray the higher first cost of the systems.


2.  The Real Energy Efficiency Numbers

Hello. This is Greg Zimmerman, executive editor of Building Operating Management magazine.

Today’s tip involves energy claims of LEED-certified buildings and other new facilities purported to be energy efficient.

Most of you are probably familiar with claims such as this: “Our new LEED-certified building is expected to save more than 35 percent on energy compared to similar buildings.” It’s certainly possible that this claim may be true, eventually. It’s just as likely that it’s not.

The thing is, those numbers are based on pre-construction energy models. And while most are fairly accurate at the time they’re run, dozens of things change over the period between when the energy calculations are done and the building is actually completed and occupied. Most experts recommend using pre-construction energy efficiency numbers only as a guide, not a set-in-stone figure.

Most experts also say it takes three years of a building being in service before an accurate and consistent energy claim can be made. During the first year, when equipment is new, there are usually problems that need to be ironed out and tweaks made, even for commissioned building. The second year is when the operations staff finally begins to get the hang of how to run the building at peak efficiency, and the third year is when it finally all comes together to establish a fairly accurate number that will be serve as a solid baseline going forward.

Of course, benchmarking and metering is as critical in the first few years – mainly to discover and diagnose problems – as it is in subsequent years to make sure your building is consistently energy efficient.

3.  Paths to Carbon Neutralilty

Hello. This is Greg Zimmerman, executive editor of Building Operating Management magazine.

Today’s topic is working to make your organization carbon neutral. Carbon neutrality basically requires a three-pronged approach – with varying ratios of each of the two, depending on the priorities and goals of the organization, its budget, and how fast it wants to declare itself officially carbon neutral.

The first and most important step is to reduce energy use as much as possible. There’s simply no substitute for an energy efficient building. To start, find the easy energy efficiency projects and operational changes that result in the biggest reductions with the best paybacks. Then move towards tougher projects that move the organization closer and closer to as low an energy spend as possible. Truly carbon neutral organizations are net-zero energy organizations, meaning organizations that require no energy from the grid.

A second leg to the carbon neutral stool is generating renewable energy generation onsite. This usually means using photovoltaic panels or onsite wind turbines.

A third option also involving renewables, but this one is a bit more controversial. You can purchase renewable energy certificates (sometimes just called RECs) or carbon offsets. RECs are purchased by the megawatt hour and ensure that even though the electricity is still coming from the grid, the amount of renewable energy purchased actually is being fed into the grid by some other renewable energy source. Besides helping to meet its own carbon neutral goal, purchasing RECs is one way an organization can help promote the gradual marketwide shift to renewable energy without actually generating renewable energy itself.

Carbon offsets are measured and sold as tons of carbon dioxide and can take various forms. It’s important to understand how the carbon offset company reinvests their money. For instance, buying one carbon offset unit may mean that company is planting trees Florida, or it may mean that the company is actually investing in energy efficiency and renewable energy projects. Most would agree that the latter is more useful to the ultimate goal of carbon neutrality anyway – combating climate change.

4.  When Selecting HVAC Products, Look at Part Load Performance

I�m Ed Sullivan, editor of Building Operating Management magazine. Today�s topic is the importance of the part-load performance of HVAC systems.

HVAC systems are designed to handle extreme conditions. Components of the system are sized for the hottest and coldest days of the year. On those days, the chiller or boiler is running at full load � and at maximum efficiency.

But for the rest of the year, the system is running at part load. And in the past that has meant a sharp drop off in energy efficiency.

Today, that needn�t be the case. Variable frequency drives, for example, can bring significant improvements in the part load performance of chillers. On the heating side, consider modulating boilers to achieve the same goal.

When you�re evaluating HVAC equipment, determine how often your system will be running under part-load conditions. And if that will be a frequent occurrence, look for a system that will be efficient at the part-load conditions that it will actually be facing.


RELATED CONTENT:


Energy Efficiency , Ground Source Heat Pump , Geothermal Heat

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