Ducted Heat Pump:Efficiency,Benefit,Setup,Maintenance

21 May 2023

By Debarghya Roy

Introduction

Ducted heat pump systems offer an energy-efficient way to maintain comfortable temperatures in your home. Ducted heat pumps are air source systems that utilize a compressor, condenser, evaporator coil, and expansion valve for heating and cooling.

These pumps can be used in residential and commercial settings and for zone control purposes when multiple temperature outputs are present. In terms of efficiency, ducted heat pumps may be more efficient than other heating and cooling systems due to their ability to transfer warm or cool air quickly into the space needing climate control.

Additionally, they have several advantages over traditional ductless HVAC units such as lower installation costs, better air distribution throughout the home or business area, and lack of external noise disturbance.

Ducted heat pump

Key Takeaways

Ducted Heat Pumps provide reliable heating or cooling for each room individually and can improve air distribution in the home. They are more cost-efficient than standard AC units since they evenly distribute heated or cooled air throughout a space rather than concentrating it in one area.
Selecting the right ducted heat pump is essential to obtain optimal performance and efficiency, including size, efficiency rating, heating capacity, and noise levels.
The benefits of using ducted heat pumps include reduced energy bills due to their high energy efficiency, customized temperature control via zoning with varying multiples outputs based upon external conditions preferences, and Smart Tech upgrades that allow for convenience controls with analytics workload data sent back from 7 days hourly performance breakdowns regularly.

What Is Ducted Heat Pumps

Ducted heat pumps are either air or water source systems that use ducts to carry heated or cooled air throughout a home or commercial building.

Definition And Operation

Ducted heat pumps are a mechanical heating and cooling system that uses air ducts to deliver heated or cooled air to different rooms. Heat pumps transfer thermal energy from one space to another, efficiently controlling building interior temperatures. Ducted systems typically come in three types:

air-to-air (split systems),
water source (ground source), and
Geothermal.

Each has advantages regarding climate control applications and cost savings due to energy efficiency gains.

Air-to-air models exchange hot summer inside air with cool outside air while simultaneously heating the home in winter months, so there’s more consistent temperature management year-round rather than just using standard single-cycle HVAC units, which would provide core comfort but constantly turn on and off, providing uncomfortable room temperatures due transitioning between periods of extreme indoor cooling and then scorching temperatures during switchover cycles.

Residential And Commercial Applications of Ducted Heat Pumps

Ducted heat pumps offer several advantages in both residential and commercial settings.

Residential Applications of Ducted Heat Pumps:

Room Temperature Control: Enable individual room temperature regulation via separate thermostats.
Comfort and Efficiency: Enhance comfort levels without compromising on energy efficiency.
System Longevity: Including centrifugal fans prevents stratification, reduces overall operating costs, and increases system lifespan by preventing dirt ingress.

Commercial Applications of Ducted Heat Pumps:

Customizable Temperatures: Allow for tailoring individual zone temperatures based on specific needs.
Energy Management: Advanced scheduling functions enable control over total energy consumption.
Operational Efficiency: Particularly suitable for spaces requiring 24/7 operation, such as offices or retail stores.
Cost Efficiency: Offer lower running costs compared to conventional HVAC units.
Manpower Efficiency: Minimize the need for dedicated personnel for temperature regulation.

Advantages And Disadvantages of ductless heat pumps

Advantages of Ducted Heat Pump Systems:

Energy Efficiency:
- Ducted heat pumps can provide up to three times more heating/cooling output than they consume.
- They operate more efficiently than other heating and cooling systems, reducing energy bills.
Cost-Effective:
- Despite higher initial costs due to installation and ductwork, ducted systems can offer long-term savings by reducing energy consumption.
Improved Air Quality:
- The systems reduce condensation, helping prevent mold growth.
- Advanced air filters intensively clean indoor air, capturing fine particles like dust, pollen, and other pollutants.
Zoning Capabilities:
- Modern ducted systems allow for heating or cooling specific parts of a home or building, increasing efficiency and comfort.
Smart Technology:
- High-quality ducted units come equipped with smart features, allowing greater customization and convenience.

Disadvantages of Ducted Heat Pump Systems:

Installation and Maintenance:
- The installation of a ducted system is more complicated and costly than a mini-split system, requiring professional expertise.
- Maintenance can be more demanding due to potential dust accumulation in the ducts, affecting airflow.
Design and Aesthetic Challenges:
- The complex design of ducted systems can sometimes conflict with aesthetic considerations.
- Vent placement can be challenging, with intake ports needing sufficient space and return vents needing to clear ceilings.

Ducted Heat Pumps Vs Ductless Heat Pumps

Ducted and ductless heat pump systems both offer effective and energy-efficient heating and cooling solutions. However, there are notable differences between the two that may influence which option is best suited to your specific residential or commercial application. The following table provides a comprehensive comparison of ducted and ductless heat pump systems, laying out their advantages and disadvantages for the professional reader.

Aspect	Ducted Heat Pumps	Ductless Heat Pumps
Energy Efficiency	Lower efficiency due to radiant energy losses and pumping losses from pushing air through ductwork.	Higher efficiency as air is directly supplied to each room, avoiding energy losses through ductwork.
Cost-effectiveness	Higher heating costs and longer return on investment.	Lower heating costs with immediate return on investment.
Installation Cost	Ranges from $1,500 to $10,000 depending on the system and property size.	Ranges from $2,000 to $8,200 depending on the number of indoor units and system capacity.
Variety	Three main types: air-to-air, water source, and geothermal.	Primarily available as air-to-air systems.
Aesthetics	Less visible as components are hidden within the structure of the building.	Visible indoor units mounted on walls or ceilings, potentially affecting the room’s appearance.
Indoor Air Quality	Potential for air leakage and contamination through ductwork, requiring periodic cleaning and maintenance.	Individualized filtration in each indoor unit, reducing the risk of air contamination.
Installation Complexity	Requires extensive ductwork, making it more suitable for new constructions, or buildings with existing duct systems.	Easier to install, making it suitable for retrofitting existing buildings without duct systems.
Zoned Climate Control	Less precise temperature control as conditioned air passes through the entire duct network.	Individualized control for each indoor unit, allowing for precise temperature settings in different zones.

When considering a heating and cooling system for your clients, it is essential to weigh the advantages and disadvantages of both ducted and ductless heat pump systems. While ductless systems are generally more efficient and cost-effective, ducted systems may be preferred for their aesthetic benefits or applications requiring more extensive heating and cooling, such as commercial or industrial facilities. Ultimately, the best choice will depend on your client’s specific needs, budget, and property characteristics.

Selecting The Right Ducted Heat Pump

When selecting a ducted heat pump, factors such as size, efficiency rating, heating capacity, and noise levels should be taken into account for optimal performance.

Factors To Consider

When selecting the right ducted heat pump for optimal performance and efficiency, including the following:

1. House Size – Larger houses require larger heat pumps, and a compact-ducted system is ideal for heating or cooling several smaller rooms more efficiently.

2. Efficiency – Heat pumps come in different types, such as central, mini-split, and multi-split depending on desired power source/location, which can affect operational efficiency too. Investing in an energy-efficient unit that meets current regulations is essential.

3. Cost – Carrying out research beforehand will help identify cost-effective options that are both economical initially and long-term, with running costs taken into consideration too.

4. Insulation & Ventilation – Ensure well-insulated walls, ceilings, floors, and windows within the home not only aid with energy savings but provide comfort levels both psychologically and physically throughout the year allowing you to get the maximum use of your system, whatever its purpose may be (heat or cool). Correct ventilation within the space should always be considered for a healthy atmosphere during warmer weather conditions, avoiding the build-up of condensation leading to moisture damage and infections caused by mold spores, etc.

5 Climate – Seasonal variation requires internal climatic adjustments from airflow temperatures or intensity adjustments based on external temperature readings. This is essential if ductless; then preferences need to be selected, whether single split systems or multiple, by using the Control app from Manufacturers available, providing convenience user controls plus statistical data technology backings seven days hourly analysis our most end user-friendly units allow one-touch commands extreme

Sizing For Optimal Performance And Efficiency

Ducted heat pumps must be appropriately sized for the system to operate efficiently, effectively, and cost-effectively.

The size of the space being heated or cooled, insulation levels, indoor air quality needs, climate type, and outdoor temperatures are just some of the factors that need to be considered during installation.
In addition to sizing requirements for optimal comfort, there is an investment in energy costs associated with improper sizing. For instance, if a heat pump is undersized, it may need help maintaining desired temperatures because it cannot deliver sufficient output for large spaces or demanding climates.
It’s essential, therefore, that you opt for right-sizing your ducted heat pump when making a purchase decision; this means taking into consideration all relevant factors, including but not limited to local climate conditions as well as ductwork layout both short or long ones, make different demands on HVAC systems’ software settings to see one benefit from enhanced efficiency while still achieving desired comfort levels within each temperature zone served by such climate control system at home or work.

Energy Efficiency And Savings for ducted heat Pumps

The benefits of investing in a ducted heat pump system are hard to ignore, from reduced monthly utility bills to improved indoor air quality. To get the most out of your system and maximize energy savings, select the right size for your home and invest in routine maintenance.

Calculating Energy Savings

Calculating energy savings for a ducted heat pump system is vital in determining its efficiency and whether or not it is cost-effective for the user. The SEER Rating, which stands for Seasonal Energy Efficiency Ratio rate, is an essential factor in assessing a system’s energy-saving potential as it tells you how much cooling capacity per watt of electricity the design has.

Additionally, local climate plays a vital role in determining the optimal type and size of unit needed to efficiently cool your home or business while saving on energy costs. Other considerations include usage patterns, insulation and ventilation, intelligent controls, and noise reduction.

A suitable SEER rating can drastically reduce the energy a ducted heat pump consumes and lead to significant savings over time. For instance, a SEER 21 unit can produce seasonal heating energy savings of up to 25% when switching from an attic to an indoor duct system.

The U.S. Department of Energy (DOE) ‘s Energy Saver website provides detailed information regarding estimated energy prices for different fuels, including natural gas and electricity, and tips for reducing energy consumption levels at home or in businesses that rely on ducted heat pumps.

Energy Efficient products with ENERGY STAR qualifications can also produce considerable financial savings when compared side-by-side with non-efficient counterparts. FEMP calculated that an ENERGY STAR-qualified residential air-source heat pump could save money if priced at no more than $457 above its non-efficient model’s cost.

Furthermore, tax credits, rebates, and incentives are available for those who switch to efficient ducted heat pumps, which further increase the financial savings associated with this type of investment decision.

Tax Credits, Rebates, And Incentives

Homeowners looking to invest in a ducted heat pump system can benefit from various tax credits, rebates, and federal, state, and local incentives. These incentives aim to promote the adoption of energy-efficient appliances and technologies to reduce energy consumption and carbon emissions.

Type of Incentive	Eligibility Criteria	Amount of Credit or Rebate	Deadlines or Limitations
Federal Tax Credit	Homeowners purchase and install a qualifying heat pump or heat pump water heater.	Up to $2,000 under the Inflation Reduction Act starting in 2023.	Subject to change as part of President Biden’s Investing in America plan.
State and Local Rebates	Varies by location and program. It may require purchasing an energy-efficient heat pump meeting specific standards.	Varies by location and program. Typically ranges from a few hundred dollars to more than $1,000.	Dependent on the specific rebate program and available funds.
Utility Incentives	Customers of participating utility companies who purchase and install eligible heat pump systems.	Varies by utility company and program. It can include bill credits or discounted pricing on energy-efficient equipment.	It may be limited to specific geographic regions or customer groups (e.g., low-income households).

To maximize savings and benefits, homeowners are encouraged to research and take advantage of available tax credits, rebates, and incentives when purchasing and installing a ducted heat pump system. Be sure to check each program’s eligibility requirements and deadlines, and consult with a professional or local energy efficiency expert for guidance on selecting the most cost-effective and energy-efficient option for your home.

Installation And Maintenance Of Ducted Heat Pumps

A professional contractor should complete a ducted heat pump installation and requires specific knowledge. Proper sizing, insulation requirements, refrigerant regiments, and other considerations must be considered to ensure the system runs effectively without wasting energy.

Key Considerations For Installation

Proper ductwork design and sizing are essential when installing a ducted heat pump system. Poorly designed or sized ducts can lead to several issues, including:

1. Reduced efficiency due to increased friction caused by having too-small ducts, increased dust, and pollutants that get into the system, or simply ducts that are too long for efficient airflow.

2. Higher energy costs due to the system’s poor performance as it struggles to move air through the improperly designed and sized ducts.

3. Uncomfortable living spaces due to uneven heating or cooling rooms will only be heated or cooled evenly if the airflow is consistent.

4. Overall decreased functionality as the system’s performance is impaired every time air passes through an area with improperly designed or sized ductwork.

To ensure optimal performance and efficiency, there are several key considerations when designing and sizing a ducted heat pump system for installation:

1. Ductwork should be designed by a professional experienced in proper residential HVAC installation practices according to The Good Practice Guide for Heat Pump Installation guidelines, taking into account home size and layout as well as heater/cooler placement, and obstructions such as walls, furniture, etc., that might impact airflow from individual vents/grilles.

2. Return and supply grills should be balanced appropriately according to how far apart they are in each room. This ensures air flows easily between rooms even if returns are located off centerlines in one area while supplies are elsewhere.

3. Duct runs should be kept short, fat, straight, insulated where necessary, and sealed tightly around all edges between sections using professional-grade mastic sealant.

4. Appropriate insulation levels should also be installed around any external parts of the system (such as those exposed outside) to retain conditioned temperatures inside areas where they may be lost quickly or otherwise due to direct exposure (especially during winter months).

5. Any motorized dampers used for zone control should also be correctly balanced so that ample airflow can still reach each zone when operating in manual mode rather than automatic. This helps ensure quieter operation from fans/motors, which would otherwise have them straining against closed dampers trying desperately to keep up with demands placed on them, resulting in more noise being generated from these components accordingly.

Routine Maintenance And Care of Ducted Heat Pumps

Proper maintenance is crucial in achieving optimal performance, efficiency, and longevity for ducted heat pump systems. Quality installation is essential, but regimen care must be taken to maintain the system properly. Inspecting and cleaning key components regularly ensures that the system continues to operate at maximum efficiency and extends its lifespan. Some of the main features of a ducted heat pump system that should incorporate regular maintenance:

1. Ducts: Checking for air leaks or blockages can help reduce energy loss. Keeping the ducts clean from dust and debris will also help improve airflow and overall performance.

2. Filters: Check and replace filters regularly to prevent them from clogging with particles hindering HVAC operation.

3. Blower: Cleaning coils, fan blades, and other elements in the blower assembly helps ensure optimal air delivery and improve energy efficiency.

4. Indoor Coil: Inspecting coils for dirt, dust build-up, damage, corrosion, or other obstructions is part of a technician’s responsibility when performing routine maintenance and care on a ducted heat pump system.

5. Outdoor Unit: An essential element when it comes to maintaining HVAC equipment is ensuring that the outdoor unit is kept clear of snow, ice, leaves, or other debris that might cause a decrease in efficiency or even system failure over time if not addressed on time.

6 Other components: Be sure to inspect wiring connections between the exposed wires from circuit boards and check condensate drain lines for clogs or blockages annually (or as often as needed).

Troubleshooting Common Issues of Ducted Heat Pumps

Regarding heat pumps, troubleshooting common issues can be the difference between optimal performance and an inefficient system. Identifying and fixing fundamental problems with ducted heat pumps will save time, energy, and money.

Identifying Common Problems

Ducted heat pumps can experience a variety of issues due to several factors. Faulty reversing valves, dirty air filters, or coils blocked with dust and dirt can all cause the system to run constantly or not turn on. Property owners, technicians, installers, and service staff need to have an understanding of these common problems:

1. Faulty Reversing Valves: The reversing valve enables the heat pump to switch from heating mode in winter to cooling mode in summer. If this part malfunctions, it will only allow one set, which could lead to poor performance and energy wastage.

2. Dirty Air Filters: Clogged air filters reduce airflow, causing the unit’s compressor motors to overheat, forcing them into short cycling, making them unable to produce adequate amounts of warm or cold air as required by the user’s settings reducing their overall efficiency levels significantly over time if not addressed when noticed or observed during regular maintenance checkups done at least once every 12 months depending on environmental conditions would be best advised by HVAC professionals like in this area/ community/ region, etc.

3. Blocked Coils & Condensers: Over time dust accumulates inside ducts lowering efficiency levels and affecting temperature regulation & comfort. Potential users don’t receive desired results leading more expensive runs later so why consider swapping out pieces sooner rather than later? Take a proactive approach toward maintaining optimal operation

4. Freezing problems: Heat pumps can face difficulties in extreme temperatures, as they primarily transfer heat from the outdoor environment to the indoors for cooling. This can result in ice forming, creating barriers and hindering the pump’s efficiency, affecting power usage.

In such situations, it is crucial to have a reliable technician evaluate and provide cost-effective solutions promptly, to prevent future repair expenses. The technician should ensure the equipment is operating at peak performance.

Regardless of the weather or climate, the goal is to provide comfort at reasonable prices, fitting within your budget. They are always ready to assist with any services needed, aiming to create the most comfortable atmosphere possible.

It’s crucial to detect and address these issues promptly to prevent significant damage to the system components, which could necessitate expensive replacements. Such unplanned costs could disrupt the client’s budget. Therefore, it’s prudent to maintain and upkeep the system regularly to ensure its safe and sustainable operation over time.

Fixes And Solutions

When diagnosing and resolving problems with a ducted heat pump system, it is crucial to consider the components of a complete system.Common issues can include thermostat problems, dirty air filters, clogged condensate drain lines, running constantly, or not below freezing temperatures.

Check if the programmable thermostat is set to have the heat come on: It may be necessary to adjust the programming of your programmable thermostat if you find that your heat pump isn’t turning on when it should.
Clean or replace air filters: Regularly check and change air filters as needed throughout the life of your unit for proper airflow into and out of your home. The dirty air filters will reduce efficiency and cause damage to other parts of your HVAC system over time due to inadequate pressure levels in secondary parts like blower motors.
Refrigerant checks: You need an experienced professional to accurately diagnose refrigerant leaks because they are beyond what most homeowners can handle safely and appropriately. Refrigerant checks should also be performed periodically so technicians can determine whether additional refrigerants need to be added during a maintenance call.
Specific temperature settings adjustment: If you observe insufficient warmth or cooling from your duct vents, particularly in rooms located farthest away, consider adjusting the temperature settings gradually by 5 degrees at a time until the desired outcome is attained without frequent cycling. Conversely, be cautious of high energy bills that exceed the manufacturer’s recommended device settings.
This can shorten the device’s lifespan and increase wear and tear, leading to higher repair costs later. As mentioned earlier in the article, licensed professionals should only undertake these adjustments, as self-performing these tasks carries liability risks, particularly concerning refrigerants.

Regular maintenance and care are essential for keeping ducted heat pumps operating efficiently for years. Routine maintenance tasks include cleaning or replacing air filters every three months; having an annual tune-up performed by a qualified technician; checking electrical connections; inspecting insulation around pipes leading outdoors; ensuring efficient operation of other components.

Future Trends And Innovations Ducted Heat Pump

From energy storage systems to smart home controls, homeowners and businesses need to stay up-to-date on the latest ducted heat pump technology advancements to maximize comfort and efficiency.

Emerging Technologies

The HVAC industry is expanding rapidly with the introduction of new, complex technologies. Smart homes, geothermal heating systems, and dual-fuel heat pumps are just a few advanced solutions pushing the boundaries of engineering and design in building automation.

With a greater focus on energy efficiency and user comfort, these innovative products help improve customer satisfaction while cutting long-term costs. Solutions such as intelligent control systems, solar panels for water heating, or geothermal air conditioners provide users with added convenience at an affordable price.

Ground source heat pumps powered by low greenhouse gas electricity are increasingly common too. They can considerably reduce carbon emissions compared to traditional fossil fuel sources, making them ideal for homeowners looking for eco-friendly options without compromising energy efficiency or their budget.

The Role Of Ducted Heat Pumps In Net-zero Energy Homes

Ducted heat pumps are a popular choice for net-zero energy homes as they provide efficient heating and cooling while drastically reducing the amount of electricity consumed compared to electric baseboard heaters.

Heat pumps harness energy from the air around them, reducing emissions and globally conscious living. By using higher quality equipment, correctly sizing your system to maximize performance during peak demand hours, and taking advantage of various tax credits or rebates available in your area, you can save money over time on your energy bills.

Additionally, because ducted heat pumps can act as both an air conditioner and a heater, this provides additional flexibility associated with climate control throughout any season. No matter what conditions exist outside, you’ll always have ample amounts of hot or cold air inside at all times.

Environmental Benefits And Indoor Air Quality

Ducted heat pumps reduce carbon emissions and improve indoor air quality, making these systems more energy efficient and environmentally friendly.

Reduced Carbon Emissions:
- Ducted heat pumps can reduce greenhouse gas emissions by up to 40% compared to traditional HVAC systems.
- They work by extracting warmth (or coolness) from outside air and transferring it inside the building using various components.
- Unlike regular heating systems, heat pumps don’t need fuels like natural gas or oil, thus reducing operating costs.
- Ducted heat pumps not only reduce electricity usage, but also lower carbon emissions and pollutant release into the atmosphere.
- Many utilities provide incentives for installing these systems, enhancing their cost-effectiveness.
Improved Air Quality:
- Ducted heat pumps offer superior air filtration by capturing fine particles like dust, pollen, pet dander, and other pollutants.
- These systems help reduce allergies, asthma attacks, and other respiratory issues by creating a healthier indoor environment.
- According to a 2017 report by the Environmental Protection Agency, many households have indoor airborne pollutant levels that are two to five times higher than outdoor levels, emphasizing the need for advanced filtration HVAC systems like ducted heat pumps.
- Despite being initially more expensive, ducted units incorporate multi-stage filtration schemes that work efficiently without frequent filter replacement, thus reducing operating costs over the equipment’s life cycle and ensuring continuous improved indoor air quality.

Case Studies And Commercial Applications

By exploring successful installations, readers can gain insights into the advantages and potential of using ducted heat pumps for both residential and commercial applications.

Successful Installations

When it comes to the successful installation of ducted heat pumps, there are a number of key factors that must be taken into consideration. Proper sizing and duct design are critical for optimal performance and energy efficiency. This, combined with expert installation techniques can lead to long-term returns in terms of operational cost savings, improved comfort levels, and quality air delivery.

1. Selecting an appropriately sized system appropriate for the building type/layout – Many heating and cooling systems are installed too large or small for the area they serve leading unnecessarily high energy costs due to poor efficiency ratings. For this reason, having an experienced technician who is knowledgeable about proper sizing is essential when selecting a heat pump size as commercial applications require different considerations than residential units do.

2. Utilizing efficient distribution/connectivity components – Successful installations also involve properly sealed connections between the indoor unit’s evaporator coil stator tube set and supply air register box sets in order protect from any leakage or reduction in airflow which will adversely influence the system’s overall performance.

3a Commercial settings should include tight fitting seal joints between pipes (for water source systems) or manifold connectors if installing outdoor condensing units connected directly to refrigerant lines indoors such as chilled water coils fan coils etc

4b Residential settings may benefit from reduced noise pollution due to insulated distributions

5 Implementing smart controls – Smart control integration allows homeowners and businesses alike greater control over their environment while saving on operating costs by optimizing system cycles with intelligent temperature sensors which actively monitor space conditions before making adjustments automatically via wireless networks without user interface interference neededIn addition these features often provide nearly instantaneous adjustment capabilities tailored towards specific needs even those forgotten occasionally like remotely powering down individual zones along perimeter walls during off peak periods near bedroom areas where increased air flow has been restricted while occupants sleep more soundly through noisy nights!

6 Ensuring respectful balancing comfort aesthetics & efficiency together – A part of successful installations encompasses respectfully reconciling both comfort aesthetics regarding placement layout form factor plus consistency across design elements within budget constraints integral both residential home owners’ requirements (including those associated various forms customization desires) well complex multistoried premises needing equalized fine tuning between separate multi level sections through hallway spaces connecting them

Ducted Heat Pumps For Industrial And Commercial Applications.

Ducted heat pumps offer a reliable, efficient, and cost-effective solution for maintaining comfortable temperatures in large or multiple commercial spaces. By delivering heated or cooled air directly to the space, they allow businesses to minimize energy costs while providing consistent temperature control.

On average, businesses who switched from traditional heating and cooling systems to ductedAir Source Heat Pumps (ASHP) have been able to save up 18–20% on total electricity consumption compared with previous fuel options such as oil and gas boilers.

For example, in 2019 Sainsbury’s Supermarket reduced its CO2 emissions by 5%. To achieve this carbon reduction it replaced traditional heating systems with an all-electric ASHP system sourced by Toshiba Carrier UK.

A study conducted by Cardiff University also found that installing new two-stage Daikin BEE inverter ducted fuelled units resulted in 45% decrease in overall seasonal energy consumption compared their previous four stage electric fan coil system.