Mechanical Help

Modified on Fri, 6 Sep at 12:00 PM

Mechanical Equipment

If you are rating a house without heating equipment, please follow the steps described in this article.

Name	An identifier for the Mechanical Equipment (i.e. Furnace, AC, Heat Pump #1, etc)
Type	Dropdown options referencing a Component Type (HVAC Equipment) from the Component Library for all HVAC. Component Types contain the energy performance information (i.e. equipment efficiency, capacity, etc.). Types can be edited and/or added by clicking the Edit or Add buttons below the Type Dropdown.
% [Heating/Cooling/Hot Water] Load Served	The percentage of the total load of the home that is provided by this piece of HVAC equipment. The loads for a single or multiple heating equipment and hot water equipment must total 100% for each end-use. The cooling equipment load percentage must total either 0% or 100%. For heating and cooling, we suggest either calculating this value based on HVAC capacity or based on square footage served. Sq ft. served example: A heating system serves 1,500 s.f. in a 4,500 s.f. home. Set % Heating Load Served for that system to 33% (1500 / 4500). The other heating systems should make up the difference and the total should sum to 100%. Capacity example: A home has two cooling systems, one 2 Ton and one 3 Ton. Set % Cooling Load Served to 40% for the first system (2 / 5) and 60% for the second system (3 / 5). For hot water, please note that according to RESNET/ANSI 301-2019, if there is more than one water heater and it is evident which water heater provides the appliance with hot water, the dishwasher and clothes washer hot water usage must be attributed to the correct water heater if there are multiple water heaters serving the home. In Ekotrope versions 2.0 and later, Ekotrope provides the percent hot water load for the clothes washer and dishwasher in the Quick Results panel under the "Energy" tab. Note: There is a known bug in algorithm versions before 4.0.0 for Air Source Heat Pump and Ground Source Heat Pump when the same equipment type is serving both - heating and cooling operation. The correct method to model the conditioning load (while avoiding the bug) is to combine both the heating and cooling mechanical equipment and use the appropriate percentage of load served.
Location	If equipment is connected to a forced air distribution system, indicate the location of the air handler, otherwise indicate the location of the equipment. Currently only impacts leakage to outside estimates for ducts not tested for leakage to outside, and only in versions 3.2 and beyond. For more information regarding ducts not tested for leakage to outside, please see this article. If the equipment is a storage water heater, indicate the location of the hot water tank. If it is a tankless water heater indicate the location of the heat source.

Distribution Systems

Heating and cooling equipment may be linked to more than one distribution system. Please read here about how Ekotrope will model this case.

System Type	Select the type of distribution system appropriate based on the proposed design and HVAC equipment. Options are Radiant, Hydronic Delivery (Radiant), Forced Air and Forced Air Ductless. For radiant systems that use fluids, please select Hydronic Delivery. The following sections will describe the specific inputs for each System Type.
Heating Equipment Served	The heating equipment that the distribution system serves. Can be none, but each distribution system must serve at least one heating or cooling system.
Cooling Equipment Served	The cooling equipment that the distribution system serves. Can be none, but each distribution system must serve at least one heating or cooling system.
Estimate Area	Area is estimated using the calculations given by ANSI/ASHRAE Standard 152-2004, Section 6.3.5.2.

Radiant or Hydronic Delivery

A radiant heating and/or cooling system refers to temperature-controlled surfaces that exchange heat with their surrounding environment through convection and radiation, but not forced air. When a radiant system uses fluid as its primary delivery mechanism, please select Hydronic Delivery (Radiant). For other radiant systems such as electric resistance heat or fireplaces, please select Radiant.

All Equipment in Conditioned Space?

Check this box if all the Radiant distribution equipment is located in the conditioned space volume and un-check it if not. This will update the Overall Duct System Efficiency (1 if checked, 0.95 if un-checked).

Forced Air Ductless

Forced Air Ductless systems distribute heating and cooling locally within the perimeter of the controlled space without the need for ducts. Ductless distribution systems are assumed to be 100% efficient, so adjusting the inputs will have no effect.

Forced Air

This includes “hydro air” systems that use a hydronic heat exchanger to feed heat through a ducted forced air system.

Untested

All Equipment in Conditioned Space?	According to RESNET 301 Standard, this indicates that “no component of the distribution system, including the air handler unit or boiler, is located outside of the conditioned space boundary.”
Leakage Default	Leaky, Uninsulated: Visible cracks or leaks in any part of the ducting system. HERS Default: No part of the ducting system should have visible leaks or cracks for air to escape as defined by RESNET 301 Standard. Proposed Reduced Leakage: For projected HERS ratings only. Specifies that the design will have < 3 CFM / 100 s.f. leakage to outdoors and < 9 CFM / 100 s.f. total leakage at a pressure differential of 25 Pa.
Overall Duct System Efficiency	Estimate of the fraction of total load lost via the distribution system as calculated based on duct location and leakage default. This cannot be tested and is not a valid input for a Confirmed HERS Report unless the HERS Default Leakage is used.
HERS/ERI Duct Testing Exemption	Indicates that all ducts and the air handler are contained in the Conditioned Space Volume and duct leakage testing is not required. When modeling the HERS/ERI rated home, a thermal distribution system efficiency (DSE) of 0.88 will be used. For more information regarding duct testing exemptions, see this article. Note: For any home that uses a duct testing exemption and is permitted after July 1, 2019, Ekotrope Version 3.2.0 or newer must be used.
IECC Duct Testing Exemption	Indicates that all ducts and the air handler are contained in the Conditioned Space Volume and duct leakage testing is not required. When modeling the IECC rated home, a thermal distribution system efficiency (DSE) of 0.88 will be used. For more information regarding duct testing exemptions, see this article. Note: For any home that uses a duct testing exemption and is permitted after July 1, 2019, Ekotrope Version 3.2.0 or newer must be used.

Tested

Sq. Feet Served	Conditioned floor area served by the distribution system.
# Return Grilles	Number of return grilles in this distribution system.
Return Duct R Value	The level of insulation enclosing the return ducts. If there is some duct area inside the thermal envelope and some outside the thermal envelope, enter the R value of the ducts outside the thermal envelope. If there are multiple levels of insulation outside the thermal envelope, please use the Duct R Value Calculator spreadsheet attached at the bottom of the page to calculate the effective R value. For ducts buried under insulation, please enter the effective R value for the buried ducts. As a conservative estimate, you may use the R value of the shortest distance between the duct and free air. Alternatively, you may use Building America's guidelines for effective buried duct R value.
Supply Duct R Value	The level of insulation enclosing the supply ducts. If there is some duct area inside the thermal envelope and some outside the thermal envelope, enter the R value of the ducts outside the thermal envelope. If there are multiple levels of insulation outside the thermal envelope, please use the Duct R Value Calculator spreadsheet attached at the bottom of the page to calculate the effective R value. For ducts buried under insulation, please enter the effective R value for the buried ducts. As a conservative estimate, you may use the R value of the shortest distance between the duct and free air. Alternatively, you may use Building America's guidelines for effective buried duct R value.
Supply Duct Area	Square footage of all supply ducts.
Return Duct Area	Square footage of all return ducts
Leakage to Outside Tested?	Uncheck this box if the home is using a duct testing exemption. The distribution system efficiency (DSE) will be estimated using the location of the air handler and ducts. For more information, please see this article. Note: For any home that uses a duct testing exemption and is permitted after July 1, 2019, Ekotrope Version 3.2.0 or newer must be used.
Leakage to Outside	Visible when Leakage to Outside Tested? is checked. Duct air leakage to outside in cubic feet per minute (CFM) measured at either a pressure differential of 25 Pa or 25 Pa per 100 sq ft of conditioned floor area. See RESNET HERS Standards for protocol on performing a duct blaster test. Leakage to Outside is a required field and is used for the energy calculation.
Total Leakage Duct Test Conditions	Specify the test conditions when the total duct leakage test was completed. The total duct leakage test is a mandatory requirement for certain energy programs and IECC-based codes.
Total Leakage	Total (leakage to anywhere) duct leakage in cubic feet per minute (CFM) measured at either a pressure differential of 25 Pa or 25 Pa per 100 sq ft of conditioned floor area. Total duct leakage is a mandatory test for 2012 & 2015 IECC code as well as ENERGY STAR 3.0 and 3.1. Total leakage is not used for the energy calculation.
Use Default Flow Rate?	Check if using default flow rate as specified by Appendix A of 2006 RESNET HERS Standards (Aug. 2011). Otherwise enter the Air Handler Flow Rate in CFM. Default flow rates are calculated as such: For electric equipment: 275 CFM per 12,000 btu/hr of nominal HVAC capacity. For fuel-fired heating equipment: 200 CFM per 12,000 btu/hr of nominal heating capacity.
Duct Location	Select the location of all or a section of ducting. Additional guidelines: For ducts located within the thermal boundary of the home, including crawl spaces and basements (but not attics): Select "Conditioned Space". For ducts located in an attic within the thermal boundary of the home, select "Conditioned Attic (insulated walls and roofdeck)". These two locations will yield the same energy consumption and scores. For ducts located in a framed floor over a garage, use the following guidance: If the ducts are legitimately on the interior side of the floor insulation and the air barrier, you can use "Conditioned space". Otherwise, you can use either "Garage" or "Exterior Walls" at your discretion. Exterior walls will use a duct loss temperature of the average between indoor and outdoor temp. Garage will use the outdoor temp plus an 11 degree buffer (heating season). These temperatures are according to ASHRAE 152 - 2004. Basement (insulated walls) refers to an unconditioned basement that is outside the primary thermal boundary, but the foundation walls are still insulated. So there are two layers of thermal boundary, but the primary boundary is the floor over the basement. Basement (uninsulated) means neither the foundation walls nor the floor over the basement are insulated. This situation would be uncommon in new construction. For ducts located in an attic with radiant barrier roof sheathing, select the appropriate radiant barrier option.
% Supply Area	Enter the percent of total duct supply area in the specified duct location.
% Return Area	Enter the percent of total duct return area in the specified duct location.

Threshold / Sampled

Only visible if Duct Leakage Testing Type is set to Threshold / Sampled. The fields are the same as when Tested, but the Total Leakage and Leakage to Outdoors fields are each replaced with two fields - one for "Threshold" and one for "Field Test" leakage. These four inputs are described below. For more information - see Threshold Ratings

Enter Leakage to Outside	Uncheck this box if the home is using a duct testing exemption. The distribution system efficiency (DSE) will be estimated using the location of the air handler and ducts. For more information, please see this article. Note: For any home that uses a duct testing exemption and is permitted after July 1, 2019, Ekotrope Version 3.2.0 or newer must be used.
Threshold Leakage to Outside	Visible when Enter Leakage to Outside is checked. Enter the Threshold Value for Duct Leakage to Outside (LtO) as determined based on the conditioned floor area of the proposed design. Replaces the Duct Leakage to Outside field. The Threshold LtO is used in the HERS Index calculations.
Field Test Leakage To Outside	Visible when Enter Leakage to Outside is checked. This represents the value that was actually tested in the field. For Threshold Ratings, the Field Test LtO must be entered in order to submit to the RESNET Registry. For Sampled ratings, this should only be entered for the units that were actually tested in the field. In both cases, it is not used in the analysis, but it is reported to the RESNET Registry.
Threshold Total Leakage	Enter the Threshold Value for Total Duct Leakage (TDL) as determined based on the conditioned floor area of the proposed design. Replaces the Total Duct Leakage field. The Threshold TDL is used in compliance calculations for various energy codes.
Field Test Total Leakage	This represents the value that was actually tested in the field. For Threshold Ratings, the Field Test TDL must be entered in order to submit to the RESNET Registry. For Sampled ratings, this should only be entered for the units that were actually tested in the field. In both cases, it is not used in the analysis or compliance calculations, but it is reported to the RESNET Registry.

HVAC Grading

This section is used to describe HVAC Grading completed by the Rater in accordance with Standard ANSI/RESNET/ACCA 310. If the first checkbox is left unchecked, Ekotrope will assume HVAC Grading has not been completed, and the relevant systems (forced air: heat pumps, air conditioners & furnaces) will be modeled as Grade III per ANSI/RESNET/ICC 301-2019 Addendum B. If the checkbox is checked you will see the following inputs.

Note: the HVAC Grading section depends on data from the Mechanical Equipment and Distribution System sections. If you modify that data, click the Refresh Grading button.

1. Design Review

Design Review Within Tolerances

Check this box if a Design Review has been conducted and the home meets the requirements described in ANSI/RESNET/ACCA 310 Section 4.

If this box is un-checked all subsequent HVAC Grading sections will receive a Grade III in accordance with Standard 310. Similarly, each section relies on the section before it receiving better than a Grade III with the exception of 4. Blower Fan Watt Draw. 5. Refrigerant Charge can receive a Grade I even if Blower Fan Watt Draw gets a Grade III.

2. Total Duct Leakage

In Sections 2-4 the inputs correspond to Distribution Systems. If Total Duct Leakage has been tested and specified in the corresponding Distribution System, the results of those inputs will be summarized here along with the Total Duct Leakage Grade determined in accordance with Standard 310 Section 5. You will also see this checkbox:

With ANSI/ACCA 5 Limit

Check to indicate if the total duct leakage does not exceed the limits specified within ANSI/ACCA 5 QI Section 5.1.1a, then Grade I shall also be designated. Note: we expect this to rarely be used.

Untested Systems will see this checkbox:

Test Exception

Check this box if the system has a total amount of supply ductwork or distribution building cavities ≤ 10 ft. in length and is entirely in Conditioned Space Volume. If this box is checked the system will receive a Grade I.

3. Blower Fan Airflow

This section relies on a Design Airflow being specified in the corresponding Distribution System section. If you would like to do better than a Grade III you will need to make sure Use Default Flow Rate is unchecked and a Design Airflow has been specified.

If the Distribution System has been tested for Total Duct Leakage you will see this box:

Measured Airflow [ft³ / Minute]

The Blower Fan volumetric airflow at operating conditions, as field-measured per ANSI/RESNET/ACCA 310 Sections 6.5, 6.6, 6.7, or 6.8.

If the Distribution System has not been tested for Total Duct Leakage then there will not be any inputs in this section. The same Test Exception is available for Blower Fan Airflow as for Total Duct Leakage, so if it is checked above, we assume it also applies to Blower Fan Airflow.

4. Blower Fan Watt Draw

Test Conducted?	This test is optional, check this box to indicate that it has been conducted.
Measured Watt Draw [Watts]	The Blower Fan Watt Draw at operating conditions, as field-measured per ANSI/RESNET/ACCA 310 Section 7.4, 7.5, 7.6, or 7.7.

5. Refrigerant Charge

Unlike Sections 2-4, Refrigerant Charge corresponds to Mechanical Equipment. If an Air Source Heat Pump or Air Conditioner is present in the Mechanical Equipment section and linked to a Distribution System, a corresponding box will be present here.

Test Conducted?	This test is optional, check this box to indicate that it has been conducted.
Test Method	Select the test method to assess Refrigerant Charge, as prescribed in Standard BSR/RESNET/ACCA 310. Options Include: Non-Invasive Weigh-In
Metering Device	If the non-invasive method is used, determine the type of metering device on the Air Conditioner or Heat Pump as prescribed in Standard BSR/RESNET/ACCA 310. Options Include: Piston/Cap Tube - either piston or capillary tube. TXV/EEV - either Thermal Expansion Value (TXV) or Electronic Expansion Valve (EEV).
Difference DTD [°F]	Only present if Piston/Cap Tube is selected. The difference between the measured suction line temperature and the Target Suction Line Temperature. Defined in ANSI/RESNET/ACCA 310 Section 8.4.3.9.6.
Difference CTOA [°F]	Only present if TXV/EEV is selected. Condensing Temperature Over Ambient (CTOA) – A constant value that represents the difference between the Condensing Temperature and the outdoor air used to cool the refrigerant in the condenser coil.
Weight Deviation [%]	Only present if Weigh-In is selected. The deviation in total refrigerant weight, as prescribed in Standard BSR/RESNET/ACCA 310.

Note: HVAC Grading applies to non-ducted systems in the following ways:

Any split systems (ducted or ductless) are subject to refrigeration charge grading (default to Grade 3).
Any packaged systems (ducted or ductless) automatically get a Grade 1 refrigerant charge.
Ductless systems (split or packaged) are not subject to blower fan airflow or blower fan watt draw grading. Raters may rely on Manufacturer’s Equipment Performance Rating rather than measurements.
HVAC grading does not apply to systems without blowers or refrigerant.

Mechanical Ventilation

If you don't know the manufacturers' specifications for ventilation systems, you can check the Home Ventilating Institute's Certified Products Directory.

If you are modeling a home with a mechanical ventilation preconditioning system, please follow the steps described in this article.

Ventilation Type	Options include: Exhaust Only - One or more exhaust fans (commonly located in bathrooms and/or kitchens) that either continuously or intermittently remove air from the home. Supply Only - An indoor fan that brings in air from outside and distributes it throughout the home. Balanced - A combination of exhaust and supply ventilation that simultaneously balances air flowing into and out of the home, keeping the indoor pressure constant. ERV - Energy-Recovery Ventilators utilize a balanced ventilation strategy, and recover both sensible and latent heat during air exchange. HRV - Heat-Recovery Ventilators are a simpler sub-type of ERVs, that recover only sensible heat during air exchange. Air Cycler - Supply-duct integrated ventilation using the central air handler with electronically controlled dampers. Also known as Central Fan Integrated Supply (CFIS) systems. Ekotrope will only account for fan energy beyond what would normally be consumed by the air handler. Fan Watts should be entered as the wattage of the air handler fan. Air Cycler w/ Supp. Fan - This is similar to a traditional Air Cycler system, but when ventilation is necessary at times that the air handler is not already on, ventilation is provided by a supplemental fan (e.g. a bathroom exhaust fan) that is wired to the Air Cycler control system rather than by the air handler itself. For these systems, the Fan Watts specified should be the Watts for the supplemental fan, not for the air handler. Note: when rating a system where a supplementary fan is used in addition to the air handler fan and both fans are used when ventilation is called for, it should be modeled as an Air Cycler and the sum of the watts of the air handler and supplementary fans should be entered into the Fan Watts field.
Can flow rate be measured?	If ventilation can be measured, it must be measured. Mark "Yes" if ventilation can be measured, otherwise mark "No." If ventilation is unmeasured, the HERS Rated home will not get credit for low infiltration measurements, and a default fan ventilation will be used for the HERS Rated home. Please see ANSI/RESNET Standard 301-2014 Addendum 39 or ANSI/RESNET Standard 301 - 2019 Table 4.2.2(1) - Specifications for the Energy Rating Reference and Rated Homes - Air exchange rate for further details. Other codes and standards will still use the user entered unmeasured ventilation rate.
Ventilation Rate	Enter the mechanical ventilation rate in [Cubic Feet / Minute]. Reference ASHRAE Standard 62.2 for recommended ventilation rates. For mechanical ventilation systems that provide fresh air to multiple dwelling units in a multifamily building, please see guidance here.
Use Default Fan Watts	If ventilation wattage is not known, mark this checkbox to use default wattage. Defaults will be chosen based on ANSI/RESNET Standard 301-2014 Addendum 39 or ANSI/RESNET Standard 301 - 2019. Default Watts/CFM can be found in ANSI 301 - 2019 Table 4.2.2(1b).
Fan Watts	If the rated or measured wattage of the ventilation fan is known specify it here. If it isn't known, check the "Use Default Fan Watts" box. For Central Fan Integrated Systems (CFIS, aka Air Cyclers) without a supplemental fan, enter the wattage consumed by the air handler at the design ventilation rate. The design ventilation rate is not the full design flow of the air handler, it is the rate of controlled outside air for Indoor Air Quality. For Air Cyclers with a supplemental fan enter the wattage of the supplemental fan not the air handler.
Operational Hours per Day	Enter the number of hours the fan is running per day.
Runs Once Every Three Hours	This box should be checked if intermittent ventilation runs at least once every three hours. This will not affect the energy consumption or HERS Index of the home, but it will affect the ASHRAE 62.2 required ventilation calculation. ASHRAE 62.2 specifies a different ventilation effectiveness for fans that run at least once every 3 hours.
Is this an inline fan?	This selection will show only for certain ventilation types. It was added to Ekotrope in September 2021 in order to support the IECC 2021 code, which has different efficacy requirements for inline fans. If left as "Unspecified," which is the default value, Ekotrope will indicate that the home does not meet IECC 2021.

If ERV or HRV are selected for type, then the following field will also be available.

Energy Recovery Percent

Specify the Adjusted Sensible Recovery Efficiency (ASRE) of the ERV or HRV. If using the HVI directory, this will be in a row listed HEATING. If there are multiple rows, please select the ASRE with the corresponding temperature and fan flow that most closely reflects the climate and fan speed that will be present.

Sections in the Quick Results>Compliance Panel show how the home's specified ventilation compares with ASHRAE 62.2 requirements.

Natural Ventilation

If this box is checked, Ekotrope will assume natural ventilation (i.e. opening the windows) during hours when it will

reduce annual cooling energy use. This is automatically assumed when calculating the HERS Index.

Ceiling Fans

If ceiling fans are modeled, they will operate in the cooling season only, at 10.5 hours/day. Ekotrope will adjust the indoor cooling setpoint to be 0.5F warmer to reflect predicted thermostat adjustments due to improved comfort.

Has ceiling fans	Check this box if the home has ceiling fans. If this is checked, Ekotrope will assume that (# of ceiling fans) = (# of bedrooms + 1).
Rated CFM / Watt	The average CFM/Watt for all installed ceiling fans. This is the labeled (per EPA guidelines) medium-speed efficiency of the ceiling fan(s) installed in the home, in cfm/Watt.

Climate Control

Has Programmable Thermostat

If this is checked, Ekotrope will assume a programmable thermostat is installed.

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