Energy Efficiency And HVAC Technology

The next overview gives a fast reference to key concerns with among the best applied sciences. As with lighting, trial installations are a good suggestion; so is working with producers and distributors.Getting essentially the most from HVAC controlsBecause a constructing’s efficiency could be dramatically improved by putting in and totally utilizing HVAC controls, it’s important to know and appropriately use these controls. The place to start out is with a detailed take a look at what is basically transpiring in your constructing, 24 hours a day, seven days per week.What is occurring with each bit of apparatus? On holidays? Weekends? Because the seasons change, do your operations change? It is very important perceive the place and the way vitality is being consumed in an effort to determine the place waste is happening and the place enhancements could be carried out. Then it’s crucial to ask, “What exactly do I want these controls to do?”Vitality administration techniques (EMS) are designed to run particular person items of apparatus extra effectively and to allow integration of apparatus, enhancing efficiency of the system. In a typical EMS, sensors monitor parameters reminiscent of air and water temperatures, pressures, humidity ranges, movement charges, and energy consumption. From these efficiency factors, electrical and mechanical tools run instances and setpoints are managed.Seven-day scheduling gives hour-to-hour and day-to-day management of HVAC and lighting techniques and might account for holidays and seasonal modifications. Because the title implies, night time temperature setback permits for much less cooling in summer time and fewer heating in winter throughout unoccupied hours.Optimum begin/cease permits your entire system to look forward a number of hours and, relative to present circumstances, make choices about the best way to proceed; this permits the system to ramp up slowly, avoiding morning demand spikes or pointless run instances.Peak electrical demand could be managed by sequencing followers and pumps to start out up one after the other slightly than and by shutting off items of HVAC tools for brief durations (as much as 30 minutes), which ought to solely minimally have an effect on house temperature. Economizers scale back cooling prices by profiting from cool out of doors air. Provide-air temperature-reset can stop extreme reheat and assist scale back chiller load.An EMS can present an abundance of details about constructing efficiency, however somebody has to determine what they need the EMS to do after which give it instructions. Calibrating controls, testing and balancing are key to any well-maintained HVAC system, however are particularly vital to optimize management efforts.Variable velocity drives and energy-efficient motorsVariable velocity drives (VSDs) are practically at all times advisable as a dependable and cost-effective improve.VSDs are worthwhile the place tools is outsized or often operates at part-load circumstances. Financial savings of as much as 70 p.c could be achieved by putting in VSDs on fan motors working at part-load circumstances. They could be utilized to compressor or pump motors and are usually utilized in variable air quantity (VAV) techniques. They’re additionally value efficient in water-side functions. Backward-inclined and airfoiled followers are the most effective VSD candidates.Air-handler configurations managed by variable inlet vanes or outlet dampers squander vitality at part-load circumstances. Utilizing throttle valves to cut back movement for smaller pumping masses can be inefficient. The effectivity of motors begins to drop off steeply once they run at lower than 75 p.c of full load; they’ll eat over twice as a lot energy because the load requires. VSDs function electronically and frequently modify motor velocity to match load.The ability to run the VSD is proportional to the dice of the velocity (or movement), which is why this expertise is so environment friendly. If the velocity is decreased by simply 10 p.c, a 27 p.c drop in energy consumption ought to consequence. A VSD pilot examine carried out by EPA discovered that VSD retrofits realized an annual common vitality financial savings of 52 p.c, a mean demand financial savings of 27 p.c and a 2.5-year easy payback.Carry out harmonic, energy issue, electrical load, and torsional analyses earlier than choosing a VSD. Although harmonic and energy issue issues usually are not widespread in VSD functions, VSDs ought to usually be geared up with integral harmonic filters (or a three-phase AC line reactor) and inner energy issue correction capacitors (or a single capacitor on the VSDs’ predominant energy line). Basically, this tools will not be normal and have to be specified.Improved design and higher supplies improve the efficiency of energy-efficient motors, which use three to eight p.c much less vitality than normal motors; items with efficiencies of 95 p.c can be found.To attain most financial savings, the motor should even be correctly matched with its load, rising run time at peak effectivity. Motors function finest when operating at 75 to 100 p.c of their totally rated load; motors routinely working beneath 60 p.c of rated capability are prime candidates for retrofit. For motors whose masses fluctuate, VSDs also needs to be thought-about.Smaller, extra environment friendly motors are integral to a system downsizing stratagem; downsizing a 75 horsepower normal motor to a 40 horsepower energy-efficient mannequin will end in vitality financial savings of 15 p.c.Some energy-efficient motors have much less “slip” than standard-efficiency motors, inflicting energy-efficient motors to run at barely greater speeds; contemplate a bigger pulley to compensate for the upper velocity and to maximise vitality financial savings. Putting in a brand new pulley or adjusting the present one can be an alternative choice to a VSD when the associated fee for the VSD is prohibitive or the load has been decreased.Enhancing fan system performanceA widespread method to enhance the effectivity of the air distribution system is to transform fixed air quantity (CAV) techniques to VAV. One authority on vitality points, E-Supply, stories that “typical (VAV) air flow requirements are only about 60 percent of full CAV flow.”VAVs reply to load necessities by various the amount of the air by means of a mix of strain controls and dampers slightly than by various the air’s temperature. Based on the air strain, fan energy and quantity of conditioned air are decreased, thus rising vitality effectivity. After all, it’s essential to keep up indoor air high quality (IAQ) when altering air dealing with techniques.To maximise financial savings, VAV parts reminiscent of VSDs, variable-pitch fan blades, diffusers, mixers, and VAV packing containers have to be working correctly; cautious zoning can be required to attain VAV optimization.E-Supply recommends contemplating the next VAV retrofit procedures:• full load discount measures and calculate the utmost and minimal air movement necessities,

• measure current fan efficiency; study duct system for doable enhancements,

• stage followers which can be in parallel configurations,

• fee the system completely,

• optimize static strain setpoint and implement reset management, and

• presumably take away return air followers.Vitality-efficient and correctly sized motors are additionally advisable together with cautious management methods. Putting in a self-contained, thermally powered machine to every diffuser can add higher management to VAV techniques by controlling particular person areas, slightly than total zones, and remove the necessity for VAV packing containers. Such a tool additionally gives VAV-style capabilities to CAV techniques.VAV retrofit prices and paybacks can differ extensively. Set up issues associated to fan management, decreased provide air distribution, location of strain sensors and their reliability, along with poor design, can diminish a VAV retrofit’s efficiency. As a result of VAV packing containers are comparatively costly and one is required for every zone, it’s usually not value efficient to partition the house into many zones. Cautious zone designation — in line with occupancy, inner masses and photo voltaic achieve — will maximize effectivity, enhance consolation and scale back reheat.When reheat can’t be eradicated, contemplate these steps to reduce it: guaranteeing thermostat calibration; rising provide air temperatures throughout the cooling season; and monitoring reheat 12 months spherical and presumably using reheat solely throughout winter months. The place reheat is used primarily to manage humidity, a desiccant wheel or a warmth pipe may be thought-about.Downsizing current VAV fan techniques is a comparatively low-cost method to save vitality when masses have been decreased or when the air distribution system was outsized to start with. The next are means to downsize followers or airflow necessities:• Scale back static strain setpoint to fulfill precise temperature and airflow necessities.

• Rightsize motors and improve to energy-efficient fashions; set up bigger pulleys.

• Exchange the present fan pulley with a bigger one; that can scale back the fan’s energy necessities by lowering its velocity.

• Be sure the fan’s velocity corresponds to the load. Lowering a fan’s velocity by 20 p.c reduces its vitality consumption by roughly 50 p.c.There are a number of methods to find out if VAV fan techniques are outsized. If a motor’s measured amperage is 25 p.c lower than its nameplate score, it’s outsized. If a fan’s inlet vanes or outlet dampers are closed greater than 20 p.c, it’s outsized. If the static strain studying is lower than the static strain setpoint when inlets or dampers are open and VAV packing containers open 100 p.c, as on a scorching summer time day, the system is outsized. Once more, make sure to contemplate IAQ necessities when downsizing air dealing with techniques.Chillers and thermal storageNo one needs to interchange a wonderfully good chiller simply due to the CFC phaseout. However as soon as load-reducing effectivity upgrades have been accomplished, it could truly be worthwhile to interchange an outsized chiller. That is very true given rising costs and tightening provides of CFC refrigerants.Outsized items 10 years or older are good candidates for substitute. A high-efficiency chiller reduces vitality prices all through its lifetime; preliminary prices are decreased as a result of the substitute chiller is smaller than the previous one. Relying on the previous unit’s effectivity and cargo, a high-efficiency chiller’s vitality consumption could be.15 to.30 kW/ton much less, lowering vitality consumption by as a lot as 85 p.c if mixed with downsizing.An alternative choice to substitute is to retrofit chillers to accommodate a brand new refrigerant and to match decreased masses. That will contain orifice plate substitute, impeller substitute and presumably compressor substitute, relying on the chiller’s specifics.Retrofitting could entail gasket and seal substitute and motor rewinding. Relying on the refrigerant and the way in which the retrofit is carried out, the chiller could lose both effectivity or capability. To find out whether or not substitute or retrofit is a greater possibility, contemplate each preliminary and life-cycle prices.Retubing the condenser and evaporator yields sizable vitality financial savings however whether or not it is smart, given its excessive value, is determined by the situation of the chiller. Water-cooled condensers are usually extra environment friendly than air-cooled items. As a result of condenser water flows by means of an open loop, it’s prone to fouling. Scale build-up will inhibit warmth switch effectivity; upkeep is due to this fact required to maintain the surfaces clear.Absorption chillers are an alternative choice to centrifugal fashions. Absorption chillers value as much as $150 per ton greater than vapor compression chillers like centrifugal items, however could be worthwhile in areas of excessive electrical demand fees or the place steam or gasoline is offered, relying on the native utility fee constructions. Utilizing a mix of the 2 chiller sorts can scale back electrical demand fees.Thermal vitality storage (TES) makes use of standard chiller tools to supply conditioned water or ice (or sometimes one other phase-change materials) in off-peak durations. Water is withdrawn from storage throughout the day or at peak hours and circulated by means of the cooling system.TES techniques could be integrated into new and current techniques and might present partial load leveling or full load shifting. TES helps lower working and upkeep prices; in some instances, a smaller chiller could be specified. Some techniques present decrease provide air and water temperatures, so air and water movement necessities could be reduce.Water-side improvementsFill materials, dimension and fan configurations have an effect on cooling tower effectivity. Mobile fill (aka movie packing) will increase effectivity over different fill sorts. Oversizing the tower to permit for nearer strategy to ambient wetbulb temperature can enhance its effectivity. Generously sizing the tower and rising its share of the chiller load could make financial sense as a result of a cooling tower’s preliminary value and vitality use per ton are lower than a chiller’s.At part-load circumstances, making use of a VSD to the fan (or pump) will enhance the tower’s effectivity. Methods with VSDs and several other followers are extra environment friendly when all tower cells are working at decreased velocity versus one or two cells at full velocity.As a result of cooling towers comprise massive warmth alternate surfaces, fouling — scale or slime build-up — could be a drawback. The effectivity of improperly handled techniques could be improved with efficient water therapy. Excessive-efficiency towers can be found; induced-draft sorts are extra in style and environment friendly than forced-draft towers. Efficiency can be improved by rising cooling floor space.In conventional pumping techniques, movement is usually fixed quantity; a throttle valve reduces movement at part-load circumstances, inhibiting effectivity.Putting in VSDs on secondary pumps in variable movement techniques, rightsizing pumps and motors to fulfill load necessities, and upgrading single loop techniques to main/secondary loop configurations can enhance the efficiency and reliability of pumping techniques. In upgrading chilled water pumps, you will need to meet most and minimal movement charges by means of the chiller.Different cooling optionsDesiccants are dehumidification supplies which could be built-in into HVAC techniques to cut back cooling masses and enhance chiller effectivity whereas enhancing indoor air high quality and luxury. Previously discovered solely in area of interest and industrial functions, desiccant cooling is extending all through industrial markets.Desiccants make sense when the associated fee to regenerate them is low in comparison with the associated fee to dehumidify beneath dewpoint and might scale back HVAC vitality and peak demand by greater than 50 p.c in some instances.Evaporative coolers present one of the vital economical and environment friendly technique of cooling, utilizing as much as 75 p.c much less vitality than vapor-compression techniques. Although preliminary value is often greater, paybacks for evaporative coolers vary between six months and 5 years. Although evaporative coolers are notably prevalent within the arid West and Southwest, they’ll service most U.S. climates. E-Supply states that, together with evaporative cooling, desiccant cooling can remove refrigerative air con in lots of climates.Hybrid techniques that combine evaporative cooling with standard HVAC applied sciences supply further alternatives. To enhance efficiency contemplate decrease air velocity; higher fill supplies; greater fan, pump and motor efficiencies, together with VSDs; higher belts or direct drive; improved housing; improved controls; and duct sealing. Correct upkeep is vital to energy-efficiency.Packaged air-conditioning items are sometimes present in buildings or constructing zones the place the cooling load is lower than 75 tons. Operating these items at half load can severely scale back effectivity. They’re usually not as environment friendly as chiller techniques however could be upgraded and rightsized when changed. Present techniques could be improved through the use of greater effectivity compressors, bigger condensers and evaporators, and VSDs, although life expectations of 10 to 12 years for these applied sciences could imply that retrofits usually are not cost-effective.Warmth pumps are among the many most energy-efficient heating and cooling applied sciences obtainable immediately. Low working prices, elevated reliability and lengthy life expectations enhance their viability. They operate finest in average climates and correct sizing is vital.Multi-unit configurations can service bigger masses and supply zoning; massive, modernized central items providing capacities of as much as 1000 horsepower or 750 kilowatts are gaining recognition. Air-to-air sort warmth pumps are the commonest due to low up-front prices; floor provide warmth pumps are essentially the most environment friendly however are likely to have greater preliminary prices.Boiler upgradesEspecially in colder climates, improved boiler efficiency — with improved gas and airflow controls over a variety of load circumstances and elevated warmth switch floor areas — can contribute considerably to vitality financial savings. Smaller items organized in modular techniques enhance effectivity as much as 85 p.c whereas small items changing these with open-loop condensing techniques shoot combustion effectivity as much as 95 p.c.Boiler retrofits, mixed with improved upkeep measures, may also enhance effectivity — as much as 90 p.c. New burners, baffle inserts, combustion controls, warm-weather controls, economizers, blowdown warmth restoration and condensate return conversions present elevated effectivity alternatives. A smaller “summer” boiler may be a very good possibility when a boiler is required 12 months spherical although at decreased capacities in hotter circumstances. The a lot smaller summer time boiler is sized for decreased masses; the primary boiler is shut down.HVAC upgrades can present great financial advantages, enhance occupant consolation and system reliability, and scale back working prices. However to maximise advantages and decrease capital funding, load-reducing measures, reminiscent of lighting upgrades, ought to precede HVAC system upgrades.