/ Field knowledge · Calculation support
The spreadsheet is not the PE stamp.
Masterbuild calculation support is PE judgment on a written basis — not a spreadsheet download. Loads, duct ESP, hydronic head, and heat-recovery-chiller screening only pay if the coincident loads are real.
Educational workflow only. These methods support engineering judgment. They are not a sealed load, a fan selection, or a guarantee of energy savings. Confirm adopted energy code, manufacturer data, and field conditions before any number reaches a drawing.
What we actually calculate
- Loads. Abbreviated Manual J / CLTD zone sheets are screening. Residential final equipment still needs ACCA-approved software (Manual J/S). A 0.2–0.3 safety factor on a blank envelope is not a load.
- Duct pressure drop. Equal-friction plus SMACNA C-factor fittings. ESP = controlling-path duct/fittings + coil + dirty-filter + devices. A safety factor does not hide missing fittings, unknown flex, or an unlisted fire damper. Kitchen grease duct is not this method — see IMC Chapter 5 / NFPA 96.
- Hydronic pressure drop. Darcy-Weisbach with a documented roughness and viscosity. Closed-loop pump head is not open-loop static head. Zero GPM is not a pump selection.
- Heat-recovery chiller (HRC / DHRC). Screen on 8,760-hour coincident heating and cooling — not the IPLV sticker. If the building is not rejecting heat when it also needs heat, the machine is extra kWh. Heating savings have to beat the extra compressor and pump energy at the actual utility rates.
Sticker COP / IPLV as “the savings”
HRC economics fail when DHW and space heat are not there at the same hour the plant is making chilled water. Send TRACE (or equivalent) 8,760 data and the heating-water reset — not a catalog kW/ton.
Related: 603 · 605 · ERV 513 · tool: duct velocity screen.
What to send
- Load: occupancy, envelope notes, existing equipment, whether a TRACE/HAP/Manual J file already exists.
- Duct/ESP: system CFM, longest run, known coil/filter ΔP, flex vs sheet metal.
- Pipe: GPM, fluid, temperature, material, index-circuit length.
- HRC: whether heating and cooling actually overlap, DHW profile if you have one, plant kW/ton if known.
If someone sized the fan from a rule of thumb
Send the CFM and the run. Masterbuild will say whether a real ESP / load / HRC screen is even on the path — or the spreadsheet still has demonstration values in it.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval.