Hybrid Model: Combining Geothermal Heat Pumps (GSHPs) with Air Source Heat Pumps (ASHPs) for Maximum Efficiency and Cost Effectiveness

Although uncommon, systems composed of a hybrid, or mix of heat pump technologies are a better solution than any single type of heat pump, or heat pump with a supplemental fossil fuel combustion heat source. Well designed hybrid heat pump systems balance upfront costs with low operating costs, resulting in maximum system efficiency, cost effectiveness, and the potential for net zero emissions.

The market for heat pumps is experiencing strong growth. The growth is propelled by recent advances in technology that make heat pumps efficient over a wider range of input and output temperatures. Also, they also can be used for both heating and cooling; a desirable feature. There are several types of heat pumps, the two main ones being ground source heat pumps (GSHPs) and air source heat pumps (ASHPs). These heat pumps are usually deployed as a single type, or in combination with a fossil fuel heat source. Hybrid heat pump systems are those that use both ASHPs and GSHPs.

Heat pumps are “all electric”. All electric heat pump systems in new buildings will soon be the norm as efficiency, sustainability, and emissions reduction goals are prioritized. This is also true in retrofits of buildings with older heating systems like steam, oil-fired warm air furnaces, and similar gas fired equipment . As power from renewables continues to grow market share, and as fully electric systems have the potential to be dominant market leaders in efficiency, the greenhouse gas emissions footprint of these buildings will be greatly reduced. Appropriately designed heat pump driven heating and cooling systems have the efficiency potential to help achieve net zero emissions goals.

Heat Pump Principles

Heat pumps move heat; from a heat source to a heat sink. For heating applications, the principal energy source, be it sub-surface ground or ambient air, is on site, sustainable, and free. Heat pumps take the freely available thermal energy from the air (ASHPs) and from the ground (GSHPs), and boost it to a higher temperature with a compression/expansion cycle. The process is reversed in summer for cooling by taking heat from inside and expelling it to the air or the ground. Heat pumps are most efficient when the difference in temperature between the source (e.g. air or ground) and the output are close. In winter, as the source temp declines, the system loses efficiency. Likewise, higher output temperatures also lower efficiency.

Leveraging Heat Pump Strengths

Here in New England, the temperature in the ground 6 feet below the surface is a steady (approx.) 55°F year round. During the heating season, removing thermal energy from the ground reduces the ground temperature around the heat exchanger. It’s not unusual for the ground temperature around a geothermal borehole or horizontal loop to drop from 55°F to below 30°F. The ground temperature gets slowly replenished, from moving groundwater for instance, but it doesn’t get back up to its starting temperature until after the heating season is over.

With ground temperatures dropping by 20°F or more, system efficiency can easily drop by 30% or more. So if a stand-alone GSHP system is being designed for high efficiency, more boreholes are required to keep the system efficient. Boreholes are expensive to drill and fit up, and they can’t be located too close together. Also, sizing for 100% of the heat load with GSHPs doesn’t make good sense economically, as the heat load only approaches 100% for a matter of hours or days in the year. The answer is to include another heat source to supplement the GSHPs. As you will see, air source heat pumps make a lot of sense to be that supplemental source of energy.

Mixing Heat Pump Types to Make Hybrid Systems

As shown in the image below, most of the time that buildings need heat, the ambient air temperatures are in the 30s, 40s and 50s°F. In eastern Massachusetts, when the temperature is below 60°F, the air temperature is above 30°F for 77% of the time!

When air temperatures are in the 50s, efficiencies between GSHPs and ASHPs are roughly equivalent because the source temperatures are the same. When outdoor air temperatures are in the 40s, the GSHPs have a marginal efficiency advantage over the ASHPs. The difference in efficiency becomes more significant when temperatures drop to the 30s and below.

It’s worth examining the charts above. Most of the heating season, air temperatures are above 30°F. So if the key objective of running a heating system is optimized seasonal efficiency rather than moment-to-moment efficiency, there is good reason to continue to use ASHPs at these above 30F temps. By not using, or by using the GSHPs only sparingly at these relatively mild temperatures, in-ground temperature remains in the 50s so that the GSHPs can be used very efficiently when air temperatures are frigid.

Planning a Hybrid GSHP ASHP System

The key to implementing an efficient and cost effective heat pump installation is with thorough technical and financial planning up front. A good plan should encompass expected energy use and cost analysis, and include monitoring and performance benchmarking over time. Up front costs for GSHPs is much higher than for ASHPs. And as shown, ASHPs are just as efficient for parts of the year. So the plan needs to identify the right balance of costs and benefits.

A feasibility study and design analysis is the best way to approach this problem. The analysis should include a site evaluation, a building evaluation, and a parametric analysis of data related to u–pfront costs, hardware efficiency estimates, and operating costs. A full design plan should also include system control recommendations for balancing the operation of the hybrid system.

To truly optimize the system performance, tracking and benchmarking must be included. Every site is different, so GSHPs will not operate exactly the same at different sites. System performance data matched with weather data, time-of-day and time-of-season data will help to fine tune the system optimization.

Contact CIMI Energy for information about prioritizing energy investments, and planning for your hybrid heat pump applications. [CIMI Energy uses computer modeling and a range of data (including heat load calculations, building occupancy patterns, hardware costs, installation costs, energy costs, manufacturers efficiency data, etc.) to determine the best system plan.]

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Proving the Financial Soundness of Investments in Energy Use Reduction

Reducing energy use in buildings often requires an investment of capital, making an obligation of some sort, or both. As with any investment, there needs to be an acceptable financial return.

Returns are usually quantified in dollars saved. When looked at strictly from a dollars point of view, the investment can be looked at like other investments. The investment might even be compared to alternatives such as repaving a parking lot, expanding a workout area, or hiring more staff. Except it should be easier to quantify the return on the investment in energy reduction. Energy consumption can be easily measured. Things like parking lot improvements and staff may be desirable, but the returns are largely guesswork.

Payback Period

One of the easiest ways to quantify energy reduction return expectations is by estimating a simple payback period. Divide the expected annual savings by the initial cost.  If an expected simple payback period is really long, like 15 or 20 years, that investment can be quickly eliminated from contention without spending any more time on it.  There are probably  alternatives out there that will get a much faster payback.

Limitations to payback period as an investment metric include not quantifying changes in maintenance costs, which are not part of the initial investment. Also not accounted, but very significant are the returns that accrue after the payback period ends.  The time value of money is not accounted for.

Discounted Cash Flow Analysis (DCF)

Discounted cash flow accounts for the time value of money, and is therefore a metric that can be used if the quick-and-easy payback period metric passes muster.  DCF provides a closer look at the attractiveness of the investment opportunity.

DCF requires using a discount rate.  Different discount rates  make large impacts on the results of the analysis.  Therefore, it’s important to use one that is realistic, and even more important, to be consistent in using the same discount rate for all DCF analyses. 

Net Present Value (NPV)

Net Present Value also accounts for the time value of money, as  DCF is used to determine NPV.    Calculating the NPV results in either a positive number or a negative number.  A positive result usually indicates that an investment is worth doing.

Where NPV is less clear is when two different investment alternatives end up with positive NPVs.  The larger NPV is usually the best.  However, if more initial capital is required to reach that higher NPV, and that capital requirement comes at the expense of other things, such as necessary maintenance, then the answer is not so clear cut.

Internal Rate of Return (IRR)

The internal rate of return is another useful metric.  It shows the discount rate where the NPV of cash flows = zero (assuming NPV is positive).   The IRR is useful for determining if an investment is worthwhile.   If the IRR is higher than the cost of capital, and there is confidence in the assumptions made to determine the IRR, then the investment is probably worthwhile.

Valuation Effects

Another consideration for energy cost reduction is how the reduction in costs effects valuation.  A change to energy assets that creates a lasting and meaningful energy cost reduction most definitely will increase the value of the property or business.  Of course, to be true, the scale of energy use reduction must have a material affect on the cost structure. 

More details about the subject of how energy costs cuts affect valuation is available in this blog post.

Other Financial Considerations

In the world of energy efficiency, there are often additional factors to consider.  Some of these factors include:

  • No money down loans
  • Low interest loans
  • Energy services agreements (ESAs)
  • Tax credits
  • Tax deductions
  • Accelerated depreciation
  • Grants
  • Discounted fuel
  • Discounted power
  • Tradeable credits, and more.

CIMI Energy Can Help

CIMI Energy can perform these financial analyses and write up reports that help you to prioritize where to focus.  

Beyond the financial aspects of these investments, there are  environmental and sustainability considerations. CIMI Energy can help with this also.  If so desired, these considerations can be considered within the reports. 

Improving Steam System Efficiency


Yesterday’s state-of-the-art steam heating systems will benefit from an upgrade to the innovative heating technology developed by Leanheat. This technology lowers energy use and costs. It does this by getting steam heating systems to run more efficiently.

Unlike hydronic systems which can easily regulate supply temperatures, steam systems always boil water to make steam. Making steam from hot water requires what’s known as a phase change (liquid to gas). Boiling water through this phase change requires a lot of extra energy*, so to wasting the energy, it’s important to limit the amount of steam produced to as close to what’s necessary to maintain comfort as possible. Steam systems are very sensitive to systemic heat loss because there’s a high temperature difference between the steam and the much lower temperatures around the system. Latent heat loss is costly, and drags down system efficiency to a much greater degree than is the case in the aforementioned hydronic systems, for example. For larger steam systems, there’s also an energy consuming vacuum pump that runs to distribute the steam. So the overall energy footprint of these systems is high.

Steam systems as they were initially constructed contained only passive energy saving technology. They relied on pipe insulation and good boiler design. But because getting even a little bit of heat through the building requires expending a lot of energy, any cycling on and off, plus overshoot effects lead to very inefficient operation.

Today’s steam systems typically operate with the first generation of active efficiency improvements. Outdoor temperature, together with a heating curve are used to limit the amount of time the boiler produces steam. For example, milder days require less heat, so by using the outdoor temperature as a factor to limit the time that steam is produced in each cycle, the costly waste of latent heat (see below) that results from overshoot (and thus overheated rooms and opening of windows) is partially avoided. The downside of this control technology, outdoor reset, is that it’s not able to account for outdoor temperature changes ahead of time, so a conservative buffer is required, which has a cost in lower efficiency.

What Leanheat technology does is take this concept of active energy saving quite a bit further, with more and better factors used to determine the amount of steam produced by the boilers. For example, rather than base the heat production of a long-lag heating system on the outdoor temperature right now, Leanheat factors in where the outdoor temperature is going (based on weather data), solar effects (e.g. expected sunshine or cloud cover), windchill effects, and so on. It also factors in how quickly room temperatures change when the boiler is running.

As a result of the Leanheat upgrade, less of a temperature buffer is required, and temperatures are more consistently comfortable throughout the building. The system also runs more efficiently, lowering costs.

More Reading

Read more about this topic in the blog post on outdoor reset here, and in the context of a building’s Unique Energy Fingerprint here.
And how lower energy costs effect property values here.

*It takes about 8,000 BTUs of energy to turn a gallon of boiling water into steam. An 80% efficient steam boiler would require over 10,000 BTU to make steam from a gallon of boiling water. The energy in the steam, know as latent heat, is given off as it condenses in the pipes and radiators.

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The Effect of Energy Cost Cuts on Property Values


Cutting energy costs has many benefits, not the least of which is increasing property values.  The example below shows the effects on property values for a $10,000 cut in energy costs.  If you consider that many properties can have their costs cut by some multiple of that figure, it’s clear that building (or business) valuations can be increased a great deal.

Investment Payback Considerations

For anyone considering the possibility of selling their property or business, the valuation should be factored into the payback equation.  That is, even if a sale were contemplated for as little as one year out, an investment in energy cost cutting technology can make good sense even though the investment exceeds the returns on energy savings in that first year.  That’s because the investment is not just lowering annual expenses, it’s also increasing the valuation by some multiple of that expense reduction. In other words, the investment results in a positive net present value.

Property Taxes

Another benefit of cutting energy costs is that the benefits over costs go directly to the bottom line.  There should be little to no effect on property taxes because the added property valuation from the cost cuts would not be seen until the building or business is sold.  In the meantime, energy cost savings accrue for the entire time that the asset upgrade is in place.

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Cutting Energy Costs to Avoid Reverse Compounding

Energy use remains a low-hanging fruit for cutting costs. For many buildings, energy cost cuts of 10-50% are easily achievable. Energy costs are the single largest expense for some buildings, meaning that cutting energy costs can have an outsized impact on a building owner’s cost structure.

By not cutting energy costs where they can, and as soon as they can, building owners incur a reverse compounding (or negative compounding) of that opportunity. The chart below shows the effect of savings lost as if it were an expense. In this example we look at $10,000 in initial energy costs, 5 levels of savings, and the opportunity costs for not taking those savings compounded at 5%.

Reverse (Negative) Compounding

Multifamily building owners, managers, and tenants all benefit when energy costs are reduced. And cost cuts are both desirable and necessary. Competition in the multifamily sector is increasing. The total number of multifamily housing units increased by 587,000 units last year (2017), the most since 1971. That increased supply ripples across the housing markets, and puts pressure on every owner and manager, whether they be condo owners, multifamily REITs, municipal housing authorities, or direct investors.

The opportunity to cut costs is greatest for those paying the energy bills. Many building owners have already made changes to lighting, and perhaps upgraded to more efficient boilers and chillers. Others have entered into contracts that shave costs from their energy suppliers. There remain many others who don’t have the capital to invest in necessary upgrades. Fortunately, for all of these groups, the biggest opportunities for cost cuts remain. These opportunities are made possible through the application of innovative technologies.

Opportunities for significant cost savings are present whether a building has central heating and cooling, pays variable time-of-day energy rates, includes heating in rent, and more. When the scale of the savings opportunity is large, as it usually is, a solution can usually be found that’s suitable for almost any building.
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Pros and Cons of Energy Services Agreements (ESAs)

Energy Services Agreements (ESAs) are an innovation in how energy is managed and paid for. ESAs provide funding for energy-related capital improvements. They also provide other benefits as described in the list that follows. As might be expected, there are limitations that organizations need to weigh when considering entering into an ESA.

Pros of ESAs

1. No capital costs for retrofit borne by building owners
2. Net cash flow positive for building owners (usually)
3. Planning and execution of capital upgrade costs handled by ESA contractor
4. Maintenance of capital equipment managed, and costs borne by contractor
5. Organization management can stay focused on organization’s mission
6. ESAs often enable needed improvements to take place more quickly
7. Larger financial benefits can accrue when an ESA enables capital upgrades to be made near-term rather than waiting for capital to become available
8.  ESA payments can be treated as an expense
9. Gas is cheaper in some locations when used in CHP

Cons of ESAs

1. Upgrades to existing energy and water assets can cause temporary disruptions that need to be planned for
2. Contracting organization must have trust in ability of contractor to plan, execute and manage properly

Energy Services Agreements (ESAs)

ABOUT ENERGY SERVICES AGREEMENTS (ESAs)
Energy Services Agreements essentially outsource your energy in a way that saves you money. Outsourcing has proven to be effective in many areas where core experience and focus are an advantage. Think about payroll services, food services, custodian services, headhunting services, etc. These are areas where outsourcing has taken hold long ago.

The production and consumption of energy has been going through big changes in recent years, leading to a great opportunity for organizations to cut energy costs significantly. To seize the opportunity, however, it takes specialized knowledge, an experienced team of engineers, and new capital equipment.

Ordinarily something like this would take a management team’s time and focus away from their core mission. It would ordinarily require a significant amount of capital to get it off the ground. Capital that could perhaps be preserved, or put to better use on something core to the mission of the organization.

So if an ESA can 1. save you money, 2. doesn’t distract your management team, and 3. requires no upfront capital, then you have a winning formula. That’s why we partner with RENEW Energy Partners, a pioneer in specialized Energy Service Agreements (ESAs) that require no upfront capital.

Advantages of an ESA
Operating Expenditures Saved Through Lower Energy Costs
ESAs save money. Typical ESAs involve replacing old, inefficient energy-consuming assets with new, more efficient assets. Examples include boilers, cooling units, lighting, building controls, etc. Experience has shown that reductions in energy use of between 30% and 50% can be achieved.

Savings Start Sooner
By moving forward with your energy upgrade through an ESA today, you start to gain the benefits of lower energy costs right away. Contrast this with an alternative scenario where you move forward with an energy upgrade independently, but 2 or 3 years further in the future. This alternative means that you miss out on 2 or 3 years of energy savings.

Lower Environmental Impact
By achieving large reductions in energy consumption, the environmental impact of operations is proportionally reduced as well. Carbon emissions in particular are reduced, thereby lowering the carbon footprint of your operations.

Increased Valuation
With an ESA, energy costs are lower, which leads to operating expenditures being lower. Therefore the profitability of the organization is typically increased. Profitability is obviously one key metric that organizations look at, as is valuation, which is also typically higher as well. A building with new HVAC, lighting and controls is valued more highly.

No Added Debt, Preservation of Capital
If an ESA bundles in all the capital, then there’s no upfront capital that’s necessary. Therefore, there’s no debt added to the balance sheet. Capital gets preserved, or deployed in other ways.

Outsourced Maintenance, Repairs & Insurance
By entering into an ESA, an organization essentially outsources all the fixed costs (i.e. equipment capital costs, maintenance, and insurance) related to the energy production. Additionally, during the length of the ESA, the ESA provider covers any equipment repairs, if any.

Less Risk of Breakdown or Failure
An organization that operates old and inefficient capital equipment bears a substantially higher risk of failure. Not everything that can go wrong is evident through inspections, or avoided through routine maintenance. The higher risk of failure leads to a higher risk of incurring repair costs, as well as going without energy for a period of time while the repair is being made.

Full Scope of Improvements Outsourced
By having an experienced team plan and manage the improvements, and optimize those improvements to maximize savings, the heavy lifting needed to make these big improvements is not placed on management.

Leveraging Team of Experts
The ESA comes backed with an experienced team of experts who have completed these types of projects in the past. The team includes financial investors, industry experts, and channel partners such as product manufacturers, engineers, and general contractors.

ESA Payments Can Be Expensed
ESA payments can be treated as a capital expense or as an operating expense.

Disadvantages of an ESA
No Depreciation
The only potential downside to entering into an ESA is that the “buyer” organization doesn’t get to depreciate the cost of the equipment. Of course, in most cases the equipment that’s being replaced is already fully depreciated, so there’s no depreciation impact in the financial statements of the organization.

Of course, if the buyer of the ESA invests in capital or labor instead of spending on the energy assets, that disadvantage is greatly mitigated, or even eliminated.

How an ESA is Priced and Paid For
With a RENEW Energy Partners ESA, no upfront payments are required. Energy audits (including a review of historical energy consumption), planning, and construction costs are all bundled into the ESA. Payments under the ESA are only a portion of the savings, so the organization making those payments is net cash flow positive from the start. The organization continues to pay its utility bills directly to the utility, which become lower, of course, after the investment in high-efficiency equipment is completed.

At the end of the term, the building owner can buy the project at fair market value or renew the ESA.

Energy Services Agreements and Their Alternatives

CIMI Energy’s funding partner is a premier provider of Energy Services Agreements (ESAs). ESAs provide organizations with off-balance sheet funding for energy retrofits. For the term of the agreement, the provider of the ESA maintains ownership of the equipment, and provides maintenance. Energy costs are paid by the customer, with the ESA provider receiving compensation through a portion of  the energy large energy savings.

Owner execution risk is low, and there are NO upfront costs.  The net result for the customer organization is a reliable and cost-saving energy system  that requires no cash and no debt.  It’s an off-balance sheet solution with short and long-term benefits. For more details on ESAs, visit CIMI Energy’s ESA page.

Alternatives to ESAs

Self Funding

Energy retrofits can be achieved in a number of other ways.  The most common way is self-funding, either with cash on hand, or with a combination of cash and borrowing.  However, because the capital costs for large energy retrofits can be very high, this requires tying up a lot of capital.  Furthermore, by planning and investing capital for purposes outside the core mission of the organization, management can get distracted, and takes on execution risks.
Nevertheless, if an organization has a lot of free capital, and no higher yielding alternative uses, this can still be a good approach.  But if the organization can use that capital for other purposes, either right away or off in the future, then it’s prudent not to spend it on an energy retrofit.

Operating Lease

There’s less upfront capital required with an operating lease, and  less execution risk than self funding.  An operating lease is essentially renting, and payments are expensed.  This method of funding is not suitable for many types of integrated hard assets such as heating and cooling equipment, and other large equipment that’s an integral part of a building system.

Capital Lease

A capital lease is attractive for having low upfront cash requirements.  The downside to capital leasing is that the responsibility for project management and ongoing maintenance falls upon the lessee.  These are small issues when the products are straightforward, as is the case with trucks, furniture, and computers.  For complex projects like large energy retrofits, this is a management responsibility that can require added manpower.

Performance Contract / Energy Services Company (ESCO)

Performance contracts, also known as Energy Savings Performance Contracts (ESPCs) or Energy Management Services (EMS) have achieved some popularity in recent years.  They provide a way to fund capital improvements for energy management, maintenance, and energy generation.  They typically bundle together investments with short and long-term paybacks, with a resulting medium-term payback for the bundle.

The ESCO is the entity that proposes the ESPC (or EMS), and that carries the responsibility for engineering & design, equipment purchasing, construction management, maintenance, training, measurement and verification (M&V), etc.

Upfront capital costs are high.  On the other hand, there is a performance guarantee for up to 20 years as part of the contract.  Savings are shared between the organization and the ESCO.

Power Purchase Agreements (PPAs)

Similar to ESAs (see at top), Power Purchase Agreements (PPAs) require no capital, and have low execution risk.  While ESAs are for efficiency, PPAs are for power, typically produced on site.  A typical example is an installation of a large power producing asset, such as a district heating plant, where power produced is billed, as is the heat (byproduct).

Property Assessed Clean Energy (PACE)

PACE loans are loans which are paid for through property taxes.  They are specific for what they can be used for, with energy reduction or efficiency upgrades being accepted investments.  As they are geography-specific, they are only available in some communities.

CIMI Energy partners have the experience and expertise to manage PACE-supported projects, and others.  Together we can find the right balance of risk, capital, project management, and ongoing equipment management to meet your goals.

Summary

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CHP (Combined Heat and Power)


CHP (Combined Heat and Power)

Combined Heat and Power (CHP), also known as cogen, or cogeneration, is a fast-growing energy technology in North America and around the world. A large reduction in energy costs (up to about 50%) is the primary reason for this growth.

For typical applications, where there is no change of fuel, the energy cost savings result from dramatically higher system efficiency (power + heat instead of just one or the other), and minimal distribution losses due to power produced on site. In many applications, another cost-saving benefit is peak shaving (the reduction of peak power load bought from the utility). Lowering peak power purchases can greatly reduce costs by avoiding demand rates when they spike.

In areas where electricity costs are high, and natural gas prices are low, CHP yields an excellent payback on investment due to the inherent efficiency in maximizing the utilization of the energy content of the fuel.

How CHP works
As its name suggests, Combined Heat and Power creates both heat and power at the same time.

Various fuels can be used for CHP, such as natural gas, oil, or biomass chips or pellets. The most efficient and cost effective systems use natural gas. Creating power from the combustion of a fuel yields heat as a byproduct.

Ordinarily, most of the heat that’s created during power production, such as at a utility-owned power plant, is wasted. That’s because heat is not transferable over distance the way electric power is. Heat has to be used nearby to where it is produced, and at the time it is produced, or it is lost.

By using the byproduct of power production, heat, CHP uses a higher proportion of the energy content of a fuel than is the case with power production alone.

The sankey diagram below provides another look at how much energy is wasted from the production of power at utilities. That wasted energy is largely in the form of heat, which is what you capture when the CHP power production is at your site.  Further energy losses from utilities occur in transmission and distribution (T&D).

Reliability and Resiliency
One of the great advantages of CHP is the capability to provide heat and power to a building even during power outages. This is a great advantage where the grid is not so reliable, or where large storm events like hurricanes, tornadoes, ice storms , and human-caused events can cut power.

Not every CHP unit is capable of providing power during a blackout. The  units that can do so have inverters to support this capability. 

Typical CHP Applications
As mentioned above, CHP is most attractive in areas where electricity costs are relatively high, and where natural gas prices are comparatively low. Applications such as large multifamily buildings, industrial plants, hospitals, and schools are all good candidates because they all use both heat and power.

Selling Electricity for a Profit with CHP
In some multifamily buildings, power comes in through a single metered connection, from which power is separately metered to individual units. In such cases, it may be possible for the landlord to pay a lower, commercial rate and charge tenants a higher, retail rate. This adds to profits, as well as to the value of the building.

Investigating CHP
CHP is worth investigating to cut energy costs, increase your capacity to produce heat, and to lower your peak power from your utility.

Take a look at the blog post on evaluating your options here.

Additional Resources

The US EPA has an in-depth overview in a 24 page PDF on their website here.

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