travel from h: in low- or medium-traffic systems, it’s 67% of maximum for three stops, dropping to 49% for more than three. For loads up to 400 kg, average P is 12% of maximum capacity; above 400 kg, it’s 8%. For mainly freight lifts, it’s 25%. The technical specification considers electric lifts with counterweights balanced at 50% of maximum load, so they move at most half of it. However, they consume energy in travels where the load doesn’t balance the counterweight (the load of ropes and electric cables, and the overcoming friction). Hydraulic lifts in the common inverted-trough type are typically un-counterweighted, so in upward direction they lift the full load (from zero to full), car, supports, and accessories, travelling downwards they dissipate the stored potential energy without further consumption. System efficiency depends on complex factors, and to account for technologies (counterweighted electric and hydraulic), the specification’s formula is more intricate; a simplification I suggested in my text “Lifts, Energy, Environment” (chapter 1.4) uses simple calculations based on plausible residential traffic models, then applies UNI 11300-6 values for practical estimates. An example provides a 50%-counterweighted gearless eletric lift with inverter and 480 kg capacity, in a 6-floor building with 20 m maximum travel and typical residential traffic. In a pessimistic scenario, average load is 22%, average travel (as per specification) 9.8 m, and with 80% efficiency, energy per average travel is about 2.75 Wh. The specification gives a similar example (480 kg, 50% counterweight, gearless inverter, 17 m max travel) with 5.8 Wh per average cycle (2.9 Wh per each travel), due to 8% average load—worse for electrics as it’s farther from 50% balance. For a hydraulic with same specifications (not recommended for 17-20 m travel), cycle energy would be notably higher. The decree does not require the lift installer to estimate a key value: average daily or annual travels. This is essential for total energy needs and the building’s overall energy performance index, and should be assessed with the designer based on the projected population and its distribution. CALCULATION EXAMPLES The example in UNI/TS 11300-6 assumes the lift performs 35 complete cycles per day, i.e., 70 average travels (25,550 per year). Under these conditions, operating energy consumption is about 0.2 kWh per day. Conversely, daily stand-by consumption, under the assumptions already described, is 2.27 kWh, so operating accounts for only 8% of the total 2.47 kWh. If traffic is low, the fixed component always exceeds the operating one; it could be reduced by switching off some equipment after inactivity, provided restart times don’t impair service too much. Using the method from my book, I simulated a 480 kg hydraulic lift with a 12 m travel, yielding 18.5 Wh per average cycle—about 4 times higher than the similar electric one. With the same daily travels as the specification example, operating needs would be 1.29 kWh, but without an inverter, the stand-by need drops to 1.27 kWh, totalling 2.56 kWh daily — same order as the UNI/TS 11300-6 electric example (slightly longer travel). However, adding a 400 W oil-heating resistor in the tank traveling 4 hours daily (thermostat-controlled) would add 1.6 kWh. All examples refer to predominantly residential buildings. Office, hotel, or other buildings may have heavier traffic. Moreover, it is known that in Italy the lifts for new non-residential buildings should have at least 630 kg capacity. ESTIMATION METHODS FOR INSTALLERS To provide the designer with average cycle energy data, the installer has three options: - Use ISO 25745-1 and 2 standards, based on actual measurements from a similar “model” system—very demanding and, in my view, unrealistic in the Italian market except for tall buildings. - Use a spreadsheet or tool to estimate from the UNI/TS 11300-6 formula (not simple but not overly complex), accounting for factors estimated in the specification. - Approximate average cycle needs per my book’s method for common capacities and travels—applicable only to “quasi-residential” buildings (small offices, hotels, schools) with 350-630 kg systems. Results are summarized in Tables 1, 2, and 3. 54 NORMATIVA DI GIUSEPPE IOTTI* NELLA MAGGIOR PARTE DEI CASI L’ASCENSORE INCIDE PER MENO DEL 3% SUL CONSUMO ENERGETICO COMPLESSIVO DELL’EDIFICIO, MA I SUOI DATI DIVENTANO COMUNQUE NECESSARI PER UNA CORRETTA RELAZIONE TECNICA In most cases, lifts account for less than 3% of a building’s overall energy consumption, but their data are nevertheless required for a proper technical report
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