ZeroHouse Lab: 72-Hour Autonomy Scenario

A 72-hour scenario tests battery size, occupant behaviour and charging opportunities. This is an assumed model, not a completed-project case.

Baseline scenario

Use the one-day Lab loads of 2.39 kWh per day. Assume unchanged use for three days, a full starting charge and no PV or generator input.

Reserve calculation

Required output energy is 2.39 × 3 = 7.17 kWh. With assumed efficiency 0.90 and usable fraction 0.80, nominal energy is 7.17/0.72 = 9.96 kWh before self-consumption and margins.

Sensitivity to use

An additional continuous 10 W over 72 hours adds 0.72 kWh at the output. Small continuous loads and inverter self-consumption therefore matter in extended outages.

Season and supplementary supply

Do not credit winter PV without a climate time series. A generator can change the balance but requires safe siting, fuel and compatible charging.

Limits and decisions

The model excludes heating, battery ageing, temperature limits and motor starts. Agree a load-reduction plan rather than assuming necessary systems can automatically be turned off.

ZeroHouse assessment diagram; not a construction detail.

Project review matrix
Item	Parameter	Check / result
Baseline	2.39 × 3	7.17 kWh
Nominal	7.17 ÷ 0.72	9.96 kWh
+10 W	10 × 72 ÷ 1000	+0.72 kWh

What this means for your project

Test several starting charge levels and winter shortfalls. The calculator yields an energy budget; inverter, protection and controls require separate selection.

Sources and scope of review

Checked: 2026-09-09. Editorial guidance; not evidence of compliance for an individual building.