Navigant Research Blog

Green Roofs Sprouting Up Globally

— September 18, 2014

Many cities have mandated increased energy efficiency in buildings and, in some cases, net zero energy use by buildings.  A variety of solutions is needed to meet these goals; some are cutting-edge digital technologies, while others have been around for thousands of years.  Green roofs, one of the oldest energy-saving technologies, are becoming increasingly popular and having an impact on sustainability efforts.

Modern green roofs employ advanced design and materials to provide residents with rooftop oases while saving energy.  There are two primary types of green roofs: extensive green roofs, which generally have 2 to 12 cm of planting medium and are designed to be virtually self-sustaining; and intensive green roofs, which are far more complex and act as rooftop parks and gardens.  Intensive green roofs have soil depths of more than 12 cm and can include shrubs, small trees, and conventional lawns.  Given the amount of materials and the additional weight required for intensive designs, they are not suitable for all roofs.  Companies such as Illinois-based TectaGreen have been installing various types of green roofs on buildings across the United States for many years.

Cool Under Cover

Green roofs have been used for centuries to provide insulation and protect roofing materials, and they provide many benefits to building owners, occupants, and the general public.  Rooftop vegetation offers several public benefits; it improves urban air quality, manages stormwater runoff, and helps moderate the urban heat-island effect.  But it’s the private benefits for building owners that are primarily driving the market for green roofs.

The most direct benefit is reducing the amount of energy required to heat and cool buildings.  Several studies have shown that installing a green roof reduces summer cooling needs and winter heat loss by as much as 26%.  Green roofing can also extend the lifespan of a roof by protecting the waterproofing membrane from ultraviolet radiation and physical damage.  Other benefits include noise reduction, the reduction of electromagnetic radiation, and compliance with building codes such as Leadership in Energy and Environmental Design (LEED).

Small but Growing

While costs for green roofs have dropped in recent years, there is an ongoing debate over their cost-effectiveness and payback period.  Installed costs of green roof systems can vary dramatically; extensive roofs (shallower) generally cost from $10 to $23 per square foot to install.  Intensive roofs can cost anywhere from $25 to $220 per square foot and may require regular maintenance.  Some argue that at those prices, green roofs cannot pay back their installation costs.  But it can also be argued that the most important benefits are those which are not easily quantified.  What’s more, compared to other, more intrusive energy efficiency measures, green roofs are relatively inexpensive.

Despite the cost, green roofs continue to be installed around the world.  Navigant Research’s recent Zero Energy Buildings report discusses the efforts underway to lower building energy consumption; green roofs represent a small but growing part of that effort.  In addition to energy efficiency, green roofs are part of a growing movement to improve the sustainability of urban environments and reconnect residents with the natural environment that their cities have largely erased.  They are sure to grow in popularity over the coming years.

 

New Study of EcoFactor Home Energy Management Offering Sparks Responses

— September 16, 2014

Cloud-based home energy management (HEM) startup EcoFactor is touting data from a new independent study showing that its system delivers significant energy savings for residential customers enrolled in Nevada utility NV Energy’s mPowered program.  The analysis, conducted by ADM, found that in the summer of 2013, homes with EcoFactor-connected thermostats reduced electricity consumption by an average of 94.68 kWh per month, or 5.5%.

The study also showed that EcoFactor reduced peak load by 2.7 kW per thermostat, more than twice the load shed claimed by Google’s Nest Labs (1.18 kW per device) and 90 times the load shed Opower estimates it can achieve through its behavioral approach (0.044 kW).

It’s important to note that NV Energy’s mPowered program, which at that time had 14,500 participating customers, was (and still is) all EcoFactor – with no other competitors involved.  So there is no head-to-head comparison with Nest devices, for instance, nor with Opower’s approach.

The closest comparison between EcoFactor and a competitor involved a Carrier two-way communicating thermostat for residential customers.  In terms of per-device hourly reduction, EcoFactor’s thermostats came out on top, with a peak reduction of 2.37 kW.  Carrier devices followed closely, at 2.33 kW.

EcoFactor’s approach is not limited to demand response (DR) events and electricity.  By persistently working in the background (similar to Nest), it can also help a homeowner reduce natural gas consumption via the thermostat, as the study points out.  The study’s authors calculated the expected natural gas savings from EcoFactor’s platform during months in Las Vegas when space heating would occur and found that they would amount to 18 therms per year.  When combined with the cooling reductions, about 635 kWh, the expected annual savings for an EcoFactor home was about $98.

The Competition Reacts

In a blog post, Yoky Matsuoka, Nest Labs’ vice president of technology, responded, “If we take a look at the hottest days in Austin, Texas (where we did a study of Nest homes last year) and compare them to similarly hot days for EcoFactor customers in Nevada, Nest customers and EcoFactor customers both reduced their peak energy use by about 1.3 kW of energy.”  This competition is healthy for the HEM sector.

It’s also helpful to contrast the EcoFactor-mPowered results with what Oklahoma Gas and Electric (OG&E) has reported from a similar smart thermostat-DR program called SmartHours.  Using Energate thermostats and the Silver Spring Networks software platform, the average participating OG&E customer saved about $191, or approximately 15%, off an annual bill in 2012.  That program has not undergone an independent study like NV Energy’s, but it shows that results can vary.

What this independent study of NV Energy’s programs shows is the need for common standards on which to evaluate HEM programs and devices, something we’ve pointed out in Navigant Research’s reports, Home Energy Management and Smart Thermostats.  Standardizing the measurement process across more utilities will help eliminate some of the confusion around the data and give key stakeholders – utilities, HEM vendors, and residential customers – more insight into what really lowers energy consumption and costs.

Lauren Callaway co-authored this blog.

 

Building Sensors Reach Vanishing Point

— September 9, 2014

Sensors play a critical role in building operations, from safety and security to optimizing building system performance.  Building energy management systems, lighting controls, and heating, ventilation, and air conditioning (HVAC) systems are slowly incorporating more sensors as their prices fall and their values rise.  Navigant Research’s report Advanced Sensors in Smart Buildings delves into the future of the market for sensors that have built-in processors, networking capability, and the capability to sense more than one phenomenon at a time.  Yet, as design elements in rooms and ceilings, most sensors, like the traditional thermostat, are unappealing appendages with little aesthetic value.  The good news is that the ugly boxes and knobs are shrinking and may disappear from view altogether.

Redwood Systems (acquired last year by networking company Commscope) recently released its third-generation light and motion sensor.  Redwood’s approach is to capture fine-grain occupancy and light levels to deliver lighting precisely to those in offices who need it, when they want it, even with shifting levels of sunlight.  Its lighting solution and accompanying open application programming interface (API) were deployed at the San Francisco headquarters of the software management firm GitHub, then promptly customized to enable the employees to tailor light levels as they see fit.  Redwood’s sensor looks like a small lump on the ceiling and can even be embedded in LED lighting systems themselves.

Sense of Control

The next generation of sensors may not look like anything.  New materials and manufacturing techniques will hide sensors from view, either embedding them in equipment or as objects to paste on surfaces as needed.  Imagine living in a house with smooth walls and ceilings.  No light switches or thermostats in view, other than as decorative objects.  Norwegian company Thinfilm has developed a printable temperature sensor that can function as both a temperature sensor and display for a myriad of applications.  Funded by PARC, Xerox’s research arm, Thinfilm has focused its efforts on thin labels for consumer products (like produce) that have tight temperature and lifetime tolerances.  Thinfilm has also developed advanced ID cards for people that can display names and access levels to different locations.  With data storage and near-field communications capability, Thinfilm’s products have the potential to leap from smart temperature labels to flat room temperature sensors with built-in displays and network communication.

The French company ISORG is also developing a technology using printed sensors.  Its flat light sensors are designed not for occupancy or light level applications, but for applications where light level variances can be used to control equipment, like consumer devices.  And it just received $8.7 million in financing,  bringing new attention to the printed sensor space.  This technology may jump into equipment themselves, like HVAC fans and pumps, where minuscule sensors can enable more granular control and system optimization.

 

Hidden Meters Provide Visible Savings

— September 8, 2014

A fundamental challenge in commercial building energy management is in understanding where all the electrons are flowing.  Most buildings have a meter that will tell the facility or energy manager how much power is being consumed, and smart meters have contributed greatly to their insight (in some parts of the world, including the United States, groups of buildings share a meter).  And many, such as apartment buildings, have dedicated meters for each tenant.

But to find out how much power is consumed by tenants or equipment, a finer grain view is needed.  It sounds easy to simply deploy more meters or submeters, watch the data flow in, and manage accordingly.  But the barriers to additional submeters, including the cost of deployment and regulatory issues, are limiting their deployment.

Most large heating, ventilation, and air conditioning (HVAC) and other large equipment vendors now sell embedded energy meters with their equipment, making energy management for large systems possible, albeit more expensive.  Today, an alternative is on the rise, in the form of in-line circuit breaker meters.  These devices snap on to the feeder wires of the breakers, recording the power used inside the cable without interfering with it.  All of these companies are touting the fast and easy installation, along with the value of actionable data for facility managers.  These are compelling arguments, especially considering the vast amount of commercial space and the massive plug loads associated with them.

Thinking Inside the Box

A few companies use these innocuous looking grey boxes as the data source to manage energy, displacing the traditional meter and submeter streams and setting up an interesting set of partnerships along the way.   Pennsylvania-based E-Mon sells a line of circuit breaker submeters that capture power and can then communicate via Ethernet (or TIA-485-A) with an energy management system (EMS).  While E-Mon has its own software package, the company recently announced a partnership with Honeywell to use its Attune Energy Dashboard service.   Similarly, Panoramic Power formed a partnership with Lucid, joining its ConnectNow partner group.  Panoramic Power sells only energy services, not the devices themselves, and uses wireless as opposed to wired solutions.

Enertiv both sells devices and EMSs, using Ethernet to communicate with the EMS.  In late July, the New York City-based company received $750,000 in seed funding, indicating the interest in this space.  This interest is rubbing off on newcomer Bractlet.  The Austin-based company, receiver of venture capital and seed funding from Start-Up Chile, sees circuit-level data as a way to validate the upfront costs needed for building retrofits and a way for building and energy managers to measure the value of retrofits.

It’s a compelling business case.  When it comes to retrofits, the first question asked is, “What will this retrofit cost me?” Followed by, “How long will it take to recoup my investment?”  The last question is the most difficult: “How will I know if those savings are actually achieved?” Bractlet, along with its competitors in this emerging space, may have the right approach to answering those questions.

 

Blog Articles

Most Recent

By Date

Tags

Clean Transportation, Electric Vehicles, Energy Storage, Policy & Regulation, Renewable Energy, Smart Energy Practice, Smart Energy Program, Smart Grid Practice, Smart Transportation Practice, Utility Innovations

By Author


{"userID":"","pageName":"Energy Efficient Buildings","path":"\/tag\/energy-efficient-buildings","date":"9\/22\/2014"}