Navigant Research Blog

The Link between Home Ownership and Energy Efficiency

— April 16, 2014

The world’s population, and how that population is housed, is undergoing a rapid transformation. Urbanization and its impact on sustainability have been well-studied in recent years. Indeed, 70% of the world’s population may live in cities by the second half of the century, but will they rent or own, and how will that affect energy efficiency?

Home ownership rates, like urbanization, are undergoing broad changes. Unlike urbanization, the direction and magnitude of the changes in home ownership vary regionally. Nonetheless, the rate of home ownership is on a wild ride. In the United States, home ownership is at an 18-year low. Meanwhile, Germany, famed for its renting culture, is facing a property rush.

The ownership of a home should influence investment decisions in energy efficiency. Renters have little incentive to invest in lowering utility bills if the paypack period is longer than the expected occupancy. Why would a renter install an LED light bulb that lasts for 20 years if he or she plans to move out in 2 years?  The value proposition of energy efficient investments is similarly poor for landlords.  For many improvements, such as better insulation and more efficient HVAC, the benefits are largely felt by tenants, but the cost is incurred by landlords.  In fact, data from the Energy Information Administration indicates that renters consume on average 33% more energy per square foot than homeowners do.  Home ownership has a profound impact on energy efficiency.

Household Energy Consumption, United States: 2009

Household Energy Consumption, United States: 2009

(Source: U.S. Department of Energy)

However, what about Germany? It is a country with a historically low ownership rate and a strong culture of renting, but it has been a beacon of innovation for home energy efficiency.  The first Passivhaus and the Passivhaus Institut are located in Germany, as is a house that generates enough electricity to meet its own needs and power a car.  Of course, ownership is only one factor.  Government regulation has played a large role in establishing Germany’s market for energy efficient homes.  In contrast, U.S. innovation in home energy efficiency is often driven by what homeowners want rather than what regulations dictate.  The Nest Learning Thermostat, for instance, was developed by Tony Fadell because he realized there was value in expanding the limited features of conventional thermostats.  Though, as fewer Americans and more Germans buy houses, it will be interesting to see how dynamics in innovation shift. After all, property ownership does change your world view.


Decoupling H, V, and AC: DOAS and More

— April 14, 2014

Buildings have long been a target for energy efficiency improvements, as they consume a substantial portion of the world’s energy supply (about 40% in the United States).  More recently, the detrimental effects of poorly designed buildings have been established and buildings have been identified as an area to improve the health of occupants.  Though heating, ventilation, and air conditioning (HVAC) systems can be used to accomplish both of these goals, they typically cannot achieve both goals simultaneously.  Conventional approaches to improving indoor air quality (IAQ), such as increasing the ventilation rate or increasing filter efficiency, require using more energy, while increases to energy efficiency (such as improving a building’s seal to reduce infiltration) can have adverse impacts on IAQ.  However, addressing the requirements of heating, ventilation, and air conditioning separately have produced innovative approaches to improve health and reduce costs.

A Flawed Paradigm

Heating, ventilation, and air conditioning are generally lumped into a single system.  Why not?  For the most part, each task requires a box with fans and coils.  Using a single rooftop unit or air handling unit to provide ventilation, filter recirculated air, and produce comfortable temperatures is convenient.  Unfortunately, a single system can have a difficult time maintaining adequate control over disparate conditions.  In practice, adequately addressing IAQ takes a back seat to maintaining space temperature.

In fact, there is evidence that traditional HVAC designs systematically under-ventilate.  Thermostatically-controlled variable air volume (VAV) systems do a poor job of matching airflow to ventilation requirements, particularly in conference and meeting rooms when they are first occupied.  More people in a room increases the generation of both heat and carbon dioxide (CO2).  However, thermostats have a dead-band, an allowable deviation between the actual and desired temperature to avoid short-cycling and simultaneous heating and cooling. As a result, there is a time lag between when the space is occupied and when more than the minimum airflow is delivered.  Moreover, depending on the conditions, the 55°F supply air can offset the temperature rise quickly and return to the minimum position as the CO2 of the space continues to rise.  Theoretically, the minimum damper position should meet the ventilation requirements of a fully occupied room, but improper damper minimums or poor controls integration can lead to under-ventilation.

Separation of IAQ and Thermal Comfort

Decoupling ventilation requirements from thermal comfort through a dedicated outside air system (DOAS) is one way to address this ventilation issue and improve IAQ.  A DOAS provides 100% outside air to a building to meet the building’s ventilation needs.  Typically, it is equipped with some form of energy recovery to precool and dehumidify or preheat and humidify supply air from what is captured from exhaust air.  As a result, the system ensures adequate ventilation and prevents the spread of contaminants between spaces.  Including a DOAS in a building design improves a building’s IAQ by managing it separately from heating and cooling requirements.

However, improving IAQ does not have to be part of HVAC at all.  Introducing filters and outside air into a system that is already designed to move air is convenient, but the same effect can be accomplished by other means.  Adding plants into a space, for instance, can help reduce CO2 and ozone.

The future of IAQ might not be in HVAC, but in the building itself.  Lauzon, a North American flooring manufacturer, has developed a flooring-based solution, called Pure Genius coating, to manage volatile organic compounds (VOCs).  The coating uses photocatalytic titanium dioxide to break down VOCs into water and CO2.  Of course, when maintaining IAQ, converting VOCs to CO2 is a bit like robbing Peter to pay Paul.  However, it shows the advances that materials are making.  Solutions to the current limitations of HVAC equipment might come from outside the mechanical universe rather than from incremental engineering improvements.


Energy Systems Group Acquires Chevron’s Federal ESCO Unit

— April 8, 2014

On April 1, Energy Systems Group (ESG), a major U.S. energy service company (ESCO) based in Newburgh, Indiana and a subsidiary of utility holding company Vectren Corp., announced that it had acquired the federal sector energy services unit of Chevron Energy Solutions, a subsidiary of Chevron USA. The unit, which consists of 48 employees, will not only expand ESG’s projects and footprint but, more importantly, will also allow ESG to play in the U.S. federal government’s indefinite-delivery, indefinite-quantity (IDIQ) ESCO market.

That market was created in February 2009 when the U.S. Department of Energy (DOE) awarded 16 ESCOs with DOE energy savings performance contracts (ESPCs).  These 16 contracts allow the selected ESCOs to provide federal agencies with up to $5 billion of performance contracts each.  The program effectively prequalified the 16 ESCOs to perform energy efficiency services for many of the federal government’s largest facilities.

Narrowing the Competitive Field

Although ESG had been an active player in the federal ESCO market through other avenues prior to the acquisition, such as utility energy services contracts (UESCs – a twist on the traditional ESPC in which federal agencies procure performance contracts through their local utilities), the acquisition allows it to narrow the competitive field for large contracts offered only to ESCOs.  Given that the federal market represents one of the most promising segments in the challenging ESCO market, as Navigant Research wrote in its report, The U.S. Energy Service Company Market, the acquisition positions ESG to benefit from the full scale of the federal ESCO market. “The federal sector is one of our primary targets for growth in the coming years,” said Greg Collins, President of ESG, when I spoke with him.  “This acquisition strengthens our position in delivering on a wider range of federal opportunities.”

Note that other ESCOs have entered the federal market through acquisition.  For example, in 2007, SAIC (now Leidos) acquired BENHAM Companies to gain access to a broader swath of federal building customers (though, this was before the establishment of the IDIQ market).

The federal sector has been a key focus for ESCOs in the United States over the last few years.  While the municipalities, universities, schools, and hospitals (MUSH) market remains a challenge due to the winding down of stimulus funding for municipal performance contracts and concerns about municipal debt, ESCOs have patiently awaited the boost to the market that was initiated by the Better Buildings Initiative, the $2 billion federal performance contracting program announced by President Obama in December 2011.

So far, the program has fallen short of its goal of achieving the $2 billion in contracts by the end of 2013. However, initial signs in 2014 are promising.  Many of the ESCOs I work with are reporting a strong flow of federal requests for proposals (RFPs) and, in the first quarter of 2014, over $230 million of federal IDIQ ESPCs had been awarded. By contrast, in all of 2013, only $362 million was awarded.  In addition, the CEO of Ameresco, George Sakellaris, announced in his company’s 2013 fourth quarter earnings call in early March that federal government ESCO activity was high.  Therefore, 2014 is looking strong for the ESCO market and ESG will be in a much better position to address it in the wake of this acquisition.


Flywheels Offer Hybrids a Mechanical Advantage

— April 4, 2014

It is often assumed that all hybrid vehicles must use a battery for energy storage.  But the essence of a hybrid powertrain is not necessarily engine-off operation, but to provide more efficient transportation over a stop/start journey drive cycle.  The key factor in this mode is to be able to recapture large amounts of energy very quickly and then reuse it, which requires high power density.  While batteries typically have a high energy density, they often do not respond well to high charge rates and may not be able to capture all the available energy from regenerative braking.  Larger vehicles, in particular, have a lot of kinetic energy to store when slowing down.

So the focus for hybrid vehicles is often high power density rather than high energy density.  It is this factor (as well as the lower cost) that has led some manufacturers, particularly Toyota, to continue installing nickel-metal hydride batteries when the rest of the industry has shifted to the higher energy density of the lithium ion battery.  But there are other options for higher power density, if total energy capacity is not an issue.  Ultracapacitors are one alternative and Navigant Research has produced a report on another option: Hydraulic Hybrid Vehicles.  However, a new alternative technology based on the flywheel is now in testing.

Powerful and Economical

Volvo Car Group has recently been conducting testing in the United Kingdom of a flywheel developed by Flybrid Automotive (now part of Torotrak) to determine the potential for fuel savings.  Initial results show a performance boost of 80 hp while improving fuel economy by up to 25%.  The testing uses real-world driving data from public roads and test tracks in both Sweden and the United Kingdom.  Volvo has installed the flywheel system on the rear axle of a front-wheel drive passenger car.  Under braking, the vehicle kinetic energy is used to spin a 6 kg carbon fiber flywheel at up to 60,000 rpm.  When the driver wants to accelerate again, the energy from the spinning flywheel drives the rear wheels directly via a specially designed transmission.

The benefits for the driver are that the engine can be switched off during some braking and accelerating maneuvers, plus there is extra power available when needed to supplement the internal combustion engine.  The Volvo test vehicle is about 1.5 seconds quicker than the standard vehicle going from 0 to 60 mph.

Mechanics of Storage

The Flybrid system uses the mechanical motion directly to power the transmission, so there are no energy losses transferring from one format to another.  Another type of flywheel system, developed for motor racing by Williams Hybrid Power (and since April 1, part of GKN), uses a flywheel driven by an electric motor.  Instead of storing energy chemically as in a battery, the energy is stored mechanically in the spinning flywheel and then converted back to electricity to be used by the electric drive motor.

Both systems use the same mechanical energy storage format and have to address the same issues.  Safety and reliability are important, as is longevity.  Cost is also important, and at present, the flywheel is a lot cheaper than a battery.  It’s good to see some alternative solutions being adopted by larger companies, and this topic will be covered in much more detail in our upcoming report on vehicle efficiency.


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