Trip Advisor, Yelp, and Amazon play an integral part of our lives by sharing user feedback openly and freely. It's time to do the same for the building sector. Explore the products and technologies used on WRL projects: the good, the bad, and the ugly. If you're interested in our feedback on a particular technology or system, contact us and we'll post our thoughts on the site.
The 3M Prestige Series Solar Film allows for control of solar gain in retrofit applications, without compromising daylighting potential. Care should be applied when selecting the film to use, including the following factors: heat strength of glass, desired reflectivity, and exposure of film to handling.
Air-to-water heat pumps appear to be gaining more attention in the commercial service water heating marketplace. Units absorb heat from a space and through a heat pump cycle, are able to generate hot water up to 140F. The unit is able to cool and dehumidify air where the heat pump is located, which can be particularly beneficial for spaces located below-grade, where dampness may be an issue. Longer-term reliability needs to be explored further with these systems, but show great promise for low and site net zero energy buildings relying heavily on electricity-based renewable energy.
The AAON RN series has the following key characteristics: variable-capacity R-410a scroll compressors, heat recovery options, exceedance of 90.1-2007 minimum efficiency requirements, and a compact footprint. WRL has incorporated AAON RN series units on multiple projects as a means to balance tight first cost requirements with a higher level of energy efficiency. The following are issues to consider when specifying the RN series: the compact footprint results in more limited provision of access for some components, as well as a higher sound footprint than a larger outdoor air-handling unit.
The AAON RL series is available in nominal airflow rates of 8,900 to 75,000 cfm. This packaged rooftop air-handling unit system line can be specified with an air-cooled, water-cooled, or evaporative-cooled condenser. The latter allows for improved energy efficiency over an air-cooled system, without the need for a separate cooling tower condenser water system.
The Acutherm VAV diffuser product line is thermally activated. An actuator with a phase-change material responds to changing room temperature. Setpoints can be selected by turning knobs hidden behind the diffuser plate. This technology allows for a higher level of thermal comfort controllability to be provided in applications with many thermal zones, without the need for a separate VAV box for each zone. Medical office buildings with exam rooms and commercial buildings with many closed offices are good candidates for this technology. Designers should exercise care when designing these systems though: pressure-independent control dampers are still needed, to keep the pressure seen at each diffuser within a certain pressure range. VAV diffusers do not suffer from dumping issues, as do traditional diffusers, as each diffuser has a plate that moves up and down to maintain a constant discharge air velocity. WRL has sucessfully incorporated the Acutherm product in its Washington DC studio, which was awarded LEED-CI v3.0 Gold in 2011.
Advantix has developed a line of liquid desiccant (lithium chloride) dehumidiciation air-handling units. These units are able to achieve very low discharge dewpoint conditions, without a tradiitional vapor compression cycle, resulting in significant energy savings. Current models, as of 2012, are challenging to incorporate in a traditional commercial building, due to limited fan pressure capability and non-standard ductwork connection configurations. We recommend keeping a close eye on Advantix's product development. Consider use of these technologies for humidity sensitive applications in ASHRAE Climate Zones 1A, 2A, and 3A.
The Aircuity system is known generically as a multi-parameter air quality monitoring system. The system relies on small diameter tubing to move air samples from monitored spaces to a centralized cabinet ("sensor suite") with sensors: temperature, relative humidity, carbon dioxide, VOC, and other parmeters can be measured. The primary benefit of this system is that multiple spaces can share one set of sensors. Calibration routines can be centralized at reduced cost. WRL recommends using multi-parameter systems for building types requiring precise control of ventialtion air, such as laboratories, hospitals, and museums. Where a building will only require a few carbon dioxide sensors, traditional sensors are still appropriate.
The airfloor system allows for incorporation of a raised floor system, with a lower cost than a traditional pedestal type raised floor. The system consists of sheet metal forms installed over a structural slab and then covered with a topping slab with a finish material as desired by the design team. The system requires 5" depth. Linear diffusers are cast directly into the topping slab. The airfloor allows the floor system to also function as a radiant slab for heating and cooling. Application of this technology requires close coordination with the vendor, structural, mechanical, and architectural disciplines.
Thermal stratification is a significant challenge for any space with a ceiling height greater than 15 feet. In high bay spaces, warm air rises to the top of the space, requiring the heating system to work harder to maintain setpoint in the occupied zone at low level. Thermal destratification devices like the Air Pear are able to throw air downward at long distances, while operating quietly. We recommend design airside heating systems with a supply air temperature no more than 15 degrees F above the target room temperature.
WRL is a strong proponent of radiant cooling and heating, due to efficient heat transfer, impact on radiant temperature, and quiet operation. Systems can be developed using aluminum radiant panel systems, pre-manufactured composite systems, and plaster-embedded capillary mat systems. The Beka system is the predominant manufacturer of capillary mats, also known as the Karo system. The system originated in Germany and has only recently made an entrance to the US market. A plaster-embedded application allows panel systems to be coupled to thermal mass, creating a higher effective cooling/heating capacity than a free-standing system. Design teams have often faced challenges implementing this technology, due to a lack case studies and pricing history in the United States. Representation in the United States is not extensive. Significantly more application information can be found at: http://www.beka-klima.de/en/ Radiant technology requires an integrated design approach for application: space cooling loads need to be kept below 30 Btu/h-sf through careful control of building enclosure and lighting heat gains.
The Capstone Microturbine in capacities of 30, 65, 200 kW. Turbines can be used as a primary electrical generator, using natural gas or bio gas as the input fuel. Proper use of turbines can increase building resiliency to grid failures and decrease overall greenhouse gas emissions, when waste heat can be reliably utilized in a cogeneration application.
Renewable energy systems have gained significant attention over the past decade. An often overlooked option is the transpired solar collector. A perforated metal screen absorbs solar radiation, allowing for pre-heating of outdoor air, as it passes through the perforated screen, upstream of an air-handling unit. This system was used for NREL's net zero energy research support facility in Golden, Colorado.
Evaporative cooling has been used for a long time, as a low-cost way to provide cooling in hot and dry climates (ASHRAE Climate Zones 1B, 2B, 3C). The adverse impact of direct evaporative cooling is an increase in humidity content within the supply air stream. The Coolerado system uses a speciazlied evaporative cooling heat exchanger to deliver cooled air, without any change in absolute humidity. The system is capable of cooling air to the outdoor air dewpoint temperature. The Department of Energy has evaluated the Coolerado system as having an EER of over 40, approximately 4 times higher than the minimum efficiency requirements for small split DX systems. We recommend discussing applications of the Coolerado system carefully with a building owner. Some care is needed to properly shut-off the system for the winter, to prevent water from affecting the unit's heat exchanger. Unit fans are not capable of a significant amount of static pressure capability. Application support is more limited than that provided by major HVAC equipment manufacturers, but is improving.
Air-cooled screw chillers have previously been known for loud operation and relatively low efficiency compared to water-cooled equipment. Recent advances by several chiller manufacturers has resulted in significantly improved efficiency and lower sound footprints. The Daikin McQuay Pathfinder chiller line provides units in three efficiency tiers, with IEER up to 19.4, in tonnages from 190 to 550. Air-cooled equipment provides benefits over water-cooled equipment: reduced water treatment requirements and fewer equipment components. Caution is required, as equipment has a larger footprint. Units need to be installed with adequate clearance to minimize recirculation effects, which can significantly derate performance. In ASHRAE climate zones 4 through 8, anti-freeze solutions may be needed.
Packaged rooftop equipment represents the highest market share of the commercial HVAC market. This equipment has traditionally not been designed for efficiency, but rather for lowest first cost. In 2011, the Department of Energy announced a high-efficiency rooftop program. The Daikin McQuay Rebel line was the first to meet the DOE requirements, with an energy profile over 70% better than required by code. Units have approximately a 20-30% higher first cost versus standard efficiency rooftop units and are aimed for institutional and commercial clients interested in lower total cost of ownership. Units are available in capacities up to 12 tons.
Fabric ductwork has been used in an increasing number of applications. Ductwork is easier to install, compared to sheet metal ductwork, due to reduced weight. Fabric ductwork can promote improved air distribution, with either through use of perforated fabric or discrete orifices. WRL recommends use of fabric ductwork as a low cost displacement ventilation diffuser. Care is needed when designing air-handling unit systems: insufficient pressure will result in sagging ductwork.
While filtration may not be a flashy element of HVAC design, filter change requirements are one of the most significant recurring maintenance items for facility managers. The Dynamic V8 system utilizes active-field technology to polarize both the media and particles in the airstream, resulting in a MERV 13-15 level of filtration, with significantly reduced longer term pressure drop. Media holding capacity is significantly greater than cartridge filters, allowing for an increased interval being filter changes. WRL has implemented the Dynamic system with fan-powered VAV box systems, allowing for filter change intervals to increase from 3 months to 2 years.
VAV boxes are typically provided with low-cost pressure based airflow measuring stations. These units are subject to a relatively high failure rate, resulting in improper delivery of ventilation air, with the potential for increased energy consumption or indoor air quality issues. The Ebtron ELF series uses thermal dispersion technology, which provides a greater level of accuracy with less potential drift over time. WRL is a strong proponent of proper design of air-handling unit systems for ASHRAE 62.1 compliance.
Commercial service hot water heating design requires care, to ensure delivery of hot water to the most remote fixture within a reasonable period, to reduce the waste of water. Commercial buildings will usually incorporate a recirculation water loop, to keep primary plumbing piping filled with heated water. Recirculation energy losses, due to pump energy, as well as heat transfer, can be substantial. An alternative is to use point-of-use heaters. Electric tankless units are compact and can be installed underneath each plumbing device that requires hot water. Temperature regulation is good. Designers should utilize care to understand a building's potable water quality and to coordinate electrical requirements early. Buildings which derive electrical energy from utility companies reliant on coal based plants should analyze the overall impact of point of use heaters on greenhouse gas emissions, versus natural gas systems.
A siginificant number of devices used in buildings require DC power, including phone chargers, computers, and other common electronic devices. These DC native devices require bulky power supplies to convert from AC to DC, which results in conversion losses as high as 50% for lower quality power supplies. As a greater number of buildings incorporate on-site renewable energy systems, which produce DC power, the concept of a DC microgrid increases in viability. The Emerge Alliance was developed to create a DC microgrid standard. The first round of certified products rely on a standard suspended ceiling grid to provide a busway for DC power. These products include LED lighting, occupancy sensors, and ceiling fans.
Wireless technology is pervasive in our lives. From a single wireless access point, dozens of devices can be controlled, without the need for hard-wired cabling. Devices can be relocated and reprogrammed using software-based solutions. The EnOncean Alliance is a consortium of companies focused on self-powered interoperable wireless building control systems. The Alliance has developed a wireless standard, as well as devices which rely on small changes in motion, pressure, light, temperature, or vibration for energy. Batteries are typically not required. The ZigBee Alliance has developed the major competing wireless standard.
Developing heating and cooling load calculations for buildings requires experience and care. While the heat transfer for building enclosure assemblies can be calculated using well developed techniques, all it takes is poor construction quality to negate the thermal performance of an enclosure system. Building envelope commissioning is now gaining more attention, which can include both blower door testing, as well as thermal imaging. In 2006, the lowest cost thermal imager cost approximately $7,500. The Fluke TiS hits a $2,000 price threshold, while still being acceptable for commercial use.
ASHRAE Standard 90.1-2010 requires the use of energy recovery in a significant number of applications. In some climate zones, energy recovery devices with both sensible and latent recovery capability are needed to achieve a 50% total energy recovery effectiveness. We often still encounter resistance from facility managers to using enthalpy wheels, due to poor past experiences from 1st generation technology. Enthalpy wheels were previously more prone to failure and could not be easily cleaned. Today's technology allows segments of wheels to be removed if damaged and also allows cleaning using a hose and mild detergent. There may be applications where small energy recovery units are needed. The Greenheck MiniVent series provides 300 to 800 cfm of make-up air in a compact package. WRL has incorporated these units in constrained spaces in conjunction with variable refrigerant flow systems.
As more and more projects seek to attain a goal of site net zero energy, innovative on-site renewable energy solutions are needed. Roof area has traditionally been a limiting factor, constraining site net zero energy buildings to low-rise buildings. Building-integrated photovoltaics (BIPV) have attracted greater attention, as a means to activate greater building enclosure area for power production. BIPV can often substitute for an exterior cladding material, helping to provide a cost trade-off that makes on-site power production more financially viable. In 2010, WRL evaluated the Pythagoras product for use on a major GSA project, but found the system to still be cost prohibitive for use. This system is now available as a product through Guardian and continues to be a novel way to address multiple building energy and indoor environmental quality issues in one product: solar gain, daylight tranmission, and power production.
Active chilled beams have continued to receive significant interest. An alternative approach is to use fan-powered VAV boxes with both a reheat and cooling coil. This hybridized system brings together attributes of a VAV system, fan coil unit system, and active chilled beam system into one system. Benefits include greater control over ventilation air supply, better emergency condensate management, and filtration potential. Active chilled beams lack filtration capability on the entire airstream.
LED lighting has proliferated significantly in recent years, with significant development by major lighting companies, as well as through research supported by the Department of Energy. Lighting for museums requires a challenging blend of beam control, longevity, track flexibility, and color rendering performance. Until recently, halogen was the only source suited to museum applications. Now, several manufacturers have developed LED fixtures, both for retrofit and new construction applications that meet the needs of curators, conservators, and lighting designers. Litelab is one of three major manufacturers (Edison Price, LSI) that have invested significant research and development in LED fixtures. Lighting designers need to carefully consider: -Fixture availability: tight beam spreads (narrow angle) are still harder to find with LED fixtures. Some designers now use a hybrid approach, blending both LED and halogen sources to properly provide object lighting. -Track system: designers have to work carefully with an Owner to select a track system that will provide sufficient long-term flexibility in support of a manufacturer with a strong R&D plan. The dynamic nature of the LED market is both cause for excitement, as well as concern. A product line available today may be discontinued in less than a year. -Life-cycle cost: LED sources have a significantly higher luminous efficacy (lumens per watt) than halogen sources. Combined with five to ten times the lifespan of halogen sources, investment in LED will provide a favorable financial return for institutions with high labor and energy costs. Energy use reductions must be evaluated holistically in relation to HVAC energy use. Most museum systems rely on constant volume with reheat systems - traditional halogen lighting provides reheat in support of dehumidification processes that would otherwise need to provided at the system (air-handling unit) level.
Modular condensing-type boilers are now used for a significant number of commercial applications. Non-condensing boilers have maximum thermal efficiency of 88%. Condensing boilers are available with efficiency up to 98%. Condensing boilers incorporate a heat exchanger to capture energy that would otherwise be lost in flue gas, to avoid condensation within exhaust piping. Designers must use care to size heating coils to lower water temperatures, to maximize condensing potential. Products like the Lochinvar Knight boiler can be used in variable primary pumping applications, with good modulation capabiliy. Other major competitors include Aerco, Patterson-Kelley, and Fulton.
Variable refrigerant flow (VRF) systems (also known as VRV) have been successfully used for over 25 years, first in Asia, then in Europe. VRF systems allow multiple indoor fan coil units to be served from a single condensing unit, with some systems capable of simultaneous cooling and heating. Systems are known for high efficiency and application flexibility. Indoor fan coil units use Sirrocco type fans, which have a low acoustic footprint. Designers must use care to provide sufficient access to fan coil units for filter change and also consider ASHRAE 15 refrigeration safety requirements. The Mitsubishi system uses a two-pipe refrigerant piping network; other manufacturers use a three-pipe system. WRL will provide commentary on two-pipe versus three-pipe systems as a separate blog post. Units are available in water-source or air-source configurations. Application note (March 2013): designers should use care when specifying twinned water-source VRF units in a variable condenser water flow application. Units are not able to natively modulate an associated control valve. Previously published application guides incorrectly indicated this as a design feature. For designers looking for variable flow applications, consider units by LG or Daikin, which are available with a specialized control module.
The Multistack modular chiller system has gained increasing popularity, due to its compact footprint. Units are particularly popular in buildings located in high density urban environments, where mechanical room spaces may be constrained. Modules are designed to fit through a standard 36" door and load onto a standard capacity passenger elevator. Modules as small as 20 tons of capacity are meant to be coupled to provide overall plant capacity up to 1,200 tons. Care needs to be exercised to provide sufficient water treatment for the condenser water loops, to prevent fouling of chiller heat exchangers. Due to the compact size of units, heat exchangers are more sensitive to fouling than a full-size centrifugal chiller. Due to the modular nature of the system, staging of compressors is performed by Multistack's native controller. The Multistack system employs a chiller water temperature reset strategy to accomodate part-load conditions. This strategy may not be conducive to applications requiring precise chilled water temperature control. We recommend careful evaluation of system volume, to prevent excessive compressor cycling. A buffer tank may be required. Alternative manufacturers include Climacool and Arctic Chill.
In hot and humid climate zones (ASHRAE 1A to 3A), as well as extremely cold climates (ASHRAE 6 and 7), energy recovery systems can significantly reduce peak heating and cooling demand, as well as energy consumption. The Munters Drycool ERV combines several technologies to create a dedicated otudoor air unit capable of efficient dehumidification. Units incorporate an energy recovery wheel, desiccant dehumidification wheel, and DX cooling system. The DX cooling system rejects heat upstream of the desiccant wheel, to provide "free" energy for the regeneration of the desiccant material. Designers should size units carefully to best balance equipment size with fan pressure drop.
The Munters Wringer Plus utilizes a air-to-air plate type heat exchanger to enhance dehumificiation capability from a standard cooling coil. Designers should use care to specify units matched to a building's space heating and cooling system. These units are can either be designed to deliver neutral-temperature ventilation air or can be designed for a traditional 55F supply air temperature to contribute to space sensible cooling.
Motor efficiency has received significantly more attention in the past decade, as a way to improve system efficiency, without the same level of complication as replacing a boiler or chiller plant, for example. Energy standards prescibe minimum efficiency requirements, based on their HP rating. Efficiency requirements tend to be more stringent, the larger the motor. The NovaTorque product line seeks to improve efficiency for motors at lower horsepower ratings, starting at 3 (93% efficiency) and 5 (92% efficiency). The current ASHRAE 90.1-2010 requirement for a 3 HP motor is 89.5%. Overall efficiency is also improved at lower operating speeds.
Post-occupancy monitoring of building performance is still not commonplace within the commercial building sector in the United States. As building owners strive to reduce operating costs further, an increased interest in post-occupancy measurement and verification has developed. Measurement and verification can only be successful with the availability of low-cost, but reliable tools. Onset Computer Corporation has long been one of the leading suppliers of field deployed dataloggers and continues to develop units with increasing accuracy, at reasonable price points. Onset is now focusing on wireless technology, to allow download of data with greater ease. Users should look carefully at datalogger specifications to ensure sufficient accuracy, suitability to the environment being measured, and calibration requirements.
The Panasonic (formerly Sanyo) HIT Double features unique characteristics, including backside power generation capability. The backside cells can increase output by an additional 30%. This power output can be maximized by installing panels over a reflective roof membrane. Most solar panels have a power output that decreases with an increase in ambient temperature. The HIT product line has a temperature coefficient that results in greater efficiency at higher temperatures. For panel installations in ASHRAE Climate Zones 1, 2, and 3, this product line can provide significantly greater real-world output than other panel technologies. We view this product within the same overall efficiency class as the SunPower E20 line.
Displacement ventilation is an air distribution strategy that introduces cool air into a zone at low velocity, typically at low level. The cool air, typically between 62-68F, pools at floor area, where it is then carried up in the thermal plumes generated by heat sources. Displacement ventilation diffusers are known for their low acoustic footprint and comfortable delivery of air. Designers must use care to design air-handling unit systems to deliver air at elevated temperature, without reducing dehumidification potential. Return air bypass is often required, to minimize the need for reheat. Close coordination with architecture is also required, as diffusers require a large free area to maintain a displacement supply air effect. Displacement ventilation is now common for performing arts centers, as well as classrooms and conference rooms.
Evaporative fluid coolers utilize the same evaporative cooling principles as a traditional open loop cooling tower, except the process fluid is not exposed to ambient conditions. Fluid is directed through a copper heat exchanger. This provides the benefit of reduced water treatment and also protects HVAC equipment from fouling. Applications include heat rejection from data center systems as well as load balancing of GeoExchange systems.
The Silverback Solar PV racking system provides significantly flexibility with relatively long span capability. The racking system allows PV arrays to span over roof penetrations like plumbing vents, roof drains, and small exhaust fans. This allows for increased exposure of panels to solar radiation.
While energy use reductions have traditionally gained the most attention in commercial building design, designers are now also focusing their attention on water use reduction. Water stress continues to increase in more parts of the world and is expected to be the next major resource of concern impacting the United States. Buildings that used the first generation of waterless urinals saw mixed results, due to the requirement for special traps needing regular replacement. Waterless urinals retrofitted into existing buildings were often problematic when existing piping was not properly pitched for proper fluid discharge. The pint (0.125 gallon per flush) urinal provides significant water savings, while addressing some of the challenges with waterless urinals. Pint urinals are now a WRL minimum standard.
The photovoltaic panel market is saturated with a variety of manufacturers. SunPower currently manufactures the most efficient panel available on the market, with average panel conversion efficiency of 20%. Selecting an appropriate panel is not straightforward, as cost, warranties, temperature performance, weight, and manufacturing capability all need to be considered. WRL will be developing a white paper on panel selection in early 2013, with annual updates on the product market.
Air-conditioning sizing requirements are based on a combination of factors: occupant load, lighting load, equipment load, building enclosure, and ventilation. Ultimately, air-conditioning is intended to satisfy human thermal comfort requirements, through control of temperature, relative humidity, air speed, and mean radiant temperature. A significant amount of energy is expended to condition air within a space, even more so with larger volume spaces with significant building enclosure exposure. What if conditioning were applied more directly? The Tempronics office chair seeks to address control of mean radiant temperature more directly, allowing a room's air temperature to float a greater amount. The chair uses thermoelectric technology to either lower or increase the chair's surface temperature, with a power consumption of approximately 25 to 75 W, significantly less than the typical 1,000 W portable space heater. We are probably most familiar with chair heating in automobiles, a highly effective mechanism. In fact, a significant amount of thermal comfort research was originally borne out of the automobile industry. This active chair may be the start of a wave of devices that seeks to couple conditioning more closely to occupants: a step beyond ceiling radiant cooling and heating. Specifiers should consider: -Integration of wiring with systems furniture to power chair. -Longer term reliability. -Parity - all users within a workgroup will need an active chair, if dramatic room temperature setpoint changes are employed. This technology is probably not appropriate for transient spaces, like conference rooms. -Productivity - gains from improved comfort could offset the added cost of an active chair relatively quickly.
Viracon is one of the leading architectural glazing suppliers. The VE1-2M series was one of the first widely used products in low-e insulating glass units, with a high visible light transmittance and a shading coefficient of 0.45. Low-e coating technology continues to advance. We recommend looking carefully at a product's light-to-solar gain (LSG) factor, particularly for ASHRAE climate zones 1, 2, 3, and 4. The higher the LSG value, the more efficient the glazing unit at rejecting solar energy, while allowing the visible spectrum to pass through. Designers should use care in selecting the appropriate color, outside reflectivity, inside reflectivity, and visible light transmittance. Do not rely solely on small glass samples to determine appropriateness for an application. The human eye is not able to distinguish differences in tint when the glass covers the entire field of vision. Viracon's color selection site can be found here: http://www.viracon.com/index.php?option=com_viracon&view=colors Other major competitors include PPG, Guardian, and Old Castle.