TREAT FAQ: Other
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How building load was turned into equipment capacity, using the equipment and distribution efficiencies, and the safety factor?
Required Output Capacity = Building Load* Safety Factor/Distribution Efficiency
Note that diversity is built in Building Load, which is based on SUNREL™ output. Return to Top
What if part of the building envelope is directly adjacent to another building? (a.k.a. party wall)
User should create a thermal model of the building in TREAT, not geometrical model. A wall should be entered in TREAT only if there is significant heat exchange through it. Notice that in TREAT we ignore (disallow) walls between heated spaces. If the wall separate heated spaces with similar temperatures, user may simply ignore it, because there is no significant temperature difference on the opposite sides of the wall. The equivalent wattage may be estimated using R-value and area of the common wall and approximate temperature difference on both sides of the wall. Watt= UA( T1-T2)/ 3.412 Return to Top
Why are there no energy savings in an electric to gas dryer conversion:
There are no energy savings involved in the fuel switchover just a large cost savings. Energy usage depends on your inputs. You can estimate it as follows:
AnnualEnergyUsage[ Btu] = ElectricityUsage[ kWh/ year]* 3414 +AnnualSecondFuelUsage[ Therm/ year]* 100000
The final number might be different due to interaction between internal heat gains and heating/cooling. Return to Top
Electric Clothes Dryers vs. Gas Dryers
For any given load of clothes that need to be dried, it will require a certain amount of Btus. Whether those Btus come from gas or electricity does not affect the amount of energy required to evaporate the water.
The gas will be less efficient (not counting power plant and transmission losses), so if anything there would be "negative" savings. This is a reasonable way to look at it We could ask users to enter the number of loads and assume some Btu per load to calculate energy usage. However, Btu per load are probably different for different dryers.
For example, imagine an extreme case when the drum does not rotate and the clothes being dried just sits in a pile inside the drier. Intuitively it seems that in this case it would take more Btus to dry the same amount of clothes. I am sure that dryer manufactures experiment with drum size, rotation speed, hot air CFM/ temperature, etc. To account for different efficiencies of dryers, TREAT asks user to enter the annual fuel consumption of the dryer instead of the number of loads. The gas dryers in the TREAT appliance library do use more Btu per year than electric dryers, just as you expect. I would check the annual usage input for the dryers that gives the questionable results. Return to Top
The savings projected by TREAT for a lighting improvement is lower than the results of my spreadsheet.
Payback and SIR for lighting may be lower than you expect due to interaction between lighting and space heating. Make sure that your spreadsheet accounts for this. Return to Top
Mechanical Ventilation in Multifamily Buildings
Typically only corridors are mechanically ventilated in multifamily buildings .Users often enter mechanical ventilation (Fan screen) of 0.63ACH for the entire building which is very unusual for a residential building. Individual apartments may also be ventilated via an individual kitchen and bath exhaust fans. If the apartments are modeled as a single space (very common) then add a single fan to this space equal to sum of all the kitchen and bath exhaust fans. E. g. 10 kitchen fans @ 80CFM = 800CFM total operating 1 hour per day. Return to Top
Does TREAT calculate the baseload for the entire building in a multifamily model?
Yes, TREAT calculates the baseload of the entire building including common area. In multifamily buildings the baseload may include common area lighting, common area laundry facilities, exterior lighting, all lighting and appliances used within all apartments. Return to Top
In the ACEEE website, why is the energy usage of their dishwashers, in kWh per year, much higher than the values given in the TREAT Appliance Library?
The "Electricity Usage kWh per Year" in the Appliance Library does not include energy used to heat hot water that is used by the appliance. The figure that is given on dishwasher labels, etc, for dishwasher energy use includes the energy to heat the hot water. TREAT uses a separate field to enter hot water usage for appliances, "Hot Water Usage Gallons/Year." A high-efficiency dishwasher has a value of 1560 gallons = 6 loads per week * 52 weeks per year * 5 gallons per load. TREAT has a domestic hot water algorithm that calculates hot water energy usage based on all domestic hot water loads in the project.
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What should the ACH be in a leaky building?
The "Weather / Defaults" menu in TREAT includes a dropdown menu which asks the user to define the building as "very leaky," "leaky," "average," "tight," or "very tight". This sets the natural ventilation ACH. Return to Top
How do I use TREAT on my VISTA machine?
For more detailed instructions on configuring VISTA for TREAT use, download our guide on VISTA compatability.
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