Can an entire apartment building be provided with backup power?

Usually not: apartment consumption belongs to the residents and far exceeds common needs. Common loads are backed up by priority, while apartments are left to the residents’ own decisions.

Where should an OSBB board start?

With a list of common loads with nameplate data and a choice of backup runtime for each priority tier. Only after that does it make sense to compare equipment and request commercial offers.

Is the calculator enough to make a decision?

The calculator gives a range and highlights gaps in the data, but the decision requires an engineering calculation, especially for elevators, pumps, three-phase loads and systems with a generator.

Backup Power for Apartment Buildings

Author: Svitlo-Lux editorial team. Published 2026-10-23, updated 2026-10-23. Review (engineering): approved (Project owner).

Backup power for an apartment building starts not with choosing equipment but with answering a question: what in this building must never be left without electricity, and for how many hours. This page gives a framework for that decision: priority tiers of loads, the order of steps for the board and links to detailed guides for each system.

What to back up: a building is not powered “entirely” at once

Residents often picture backup power as “light in the whole building”. For an apartment building this is almost never a realistic goal: the combined apartment load is comparable to that of a small enterprise, and it belongs to the residents, not to the OSBB. What gets backed up is the common property: whatever is fed from the building’s main supply and maintained by the board.

The practical approach is this: first list the common loads, then rank them by the consequences of an outage, and only then ask an engineer which source and how much energy each tier needs. This order protects against a typical mistake, where fundraising starts with choosing an inverter or a generator, and the load list appears later and forces the budget to be redone.

All figures mentioned below are guidelines for preparing a conversation with a designer. Final parameters, the connection scheme and protection are determined by a qualified engineer, and installation is carried out by a licensed contractor.

Priority tiers: from safety to comfort

The table below is a working tool for the board. It is not a standard; it helps structure the discussion: what happens in the building when the respective load disappears, and what question about backup duration to put to the designer.

Priority tiers of common loads and the consequences of an outage
Tier	Typical loads	What happens without power	Question about backup duration
0. People’s safety	Emergency and evacuation lighting, fire alarm, public address	Dark stairwells, the alert does not sound or the control panel loses supervision	How much backup the safety systems design provides and from which source
1. Life support	Water supply pumps, dispatcher communication, intercom	No water on upper floors, doors do not open, no way to call for help	How many hours the building must function without mains power in a typical outage
2. Mobility and heat	Elevators, circulation pumps of the boiler room and individual heating substations (ITP)	People trapped in a cabin, limited mobility for residents, risk of the heating circuits freezing in winter	Cabin rescue or full operation; how many minutes or hours
3. Grounds and communications	Yard lighting, barrier gate, video surveillance, network equipment	Lower security of the grounds, loss of remote monitoring	Whether this tier is needed at the OSBB’s own expense in the first phase
4. Non-critical	Decorative lighting, commercial premises, advertising	Inconvenience, but no danger	Usually handled separately from the OSBB decision, under a separate contract

How an OSBB decides: from a list to a budget

An OSBB decision usually consists of several stages. Below is the order we recommend, not legal instructions: the voting procedure and the board’s powers are set by law and your OSBB’s charter, and must be checked separately.

List of common loads. Walk through the building with an electrician and make a list: what is fed from the main supply, where the panels are, which motors, which phases. Mark each item with a priority tier.
Collecting nameplate data. Datasheets of elevators, pumps, panels and the batteries of safety systems. Mark whatever is missing as unknown: that way it will be clear where the calculation is weak.
Preliminary calculation. Use the calculator: it will show a range of power and capacity and the reasons why an engineer is needed. This is preparation for a conversation, not a design.
Engineering survey and design. An electrical or design company checks the data, motor starts, phase balance and the space for equipment, and prepares a specification.
Comparing offers. Collect several commercial offers for the same list of loads so that they can be compared on substance.
Residents’ decision and fundraising. After the budget is agreed, the OSBB makes a decision under the established procedure and organizes the collection. The platform does not accept or hold funds.

What data to collect before talking to an engineer

An engineer works quickly and accurately when given consistent data. Preparation takes a few days but saves iterations and wrong estimates.

A single-line diagram of the building’s main supply, the permitted capacity and the number of phases at the entry.
Elevator datasheets: motor power, drive type, presence of an automatic rescue device that moves the cabin to a floor, manufacturer.
Pump datasheets: shaft power, starting method, presence of a frequency converter, operating mode (alternating duty or cascade).
A list of safety systems stating the type of backup power they already have.
Temperature levels in the utility rooms where batteries could be installed.
Photos of the panels, the places for equipment and the cable routes.

Typical planning mistakes

Adding up rated power and ignoring motor inrush (starting) currents: the inverter or generator turns out to be too small to start an elevator or pump.
Not checking load distribution across phases: a single-phase backup unit cannot feed a three-phase motor, and uneven phase loading causes problems for equipment.
Taking battery capacity without accounting for the temperature in the utility room, depth of discharge and inverter efficiency.
Choosing a generator without planning ventilation, noise, fuel storage and safe changeover that does not feed voltage back into the grid.
Putting a UPS on an elevator or pump without confirming with the motor and drive manufacturer that it will tolerate such a start and mode.
Trying to solve everything at once in a single fundraiser, instead of a phased plan in which the first phase covers tiers 0 and 1.
Calling a fundraiser “ready” for contributions before the budget, authority and documents have been verified.

Seasonality and duration: why winter changes the calculation

The same equipment behaves differently in summer and winter. In winter the lights burn longer, outages last longer, batteries in a cold room deliver less and heating circulation becomes critical. In summer the loads are lighter, but overheating in the utility room also shortens battery life. That is why it is useful for the board to discuss backup for at least two seasons and to record which of them the calculation was made for.

If there is no input data by season, do not invent it: mark the field as unknown, and the calculation will show that the estimate has low confidence. This is more honest than a confident number without basis, and it tells the engineer what exactly needs to be measured.

Where to read next

Each system has its own specifics, so we describe them separately. Each page can be read independently, but it is best to start with the overview for OSBBs and the question of duration.

Backup power for an OSBB: how the board organizes the decision, roles and documents.
Backup power for an elevator: starting, rescue mode, questions for the manufacturer.
Backup power for pumps and water supply: duty cycles, booster set, tanks.
Backup power for the boiler room and ITP: circulation, automation, the cold season.
Emergency lighting for stairwells: self-contained luminaires or a central source.
Intercom, internet and fire safety without power: low-voltage systems.
Generator or inverter for an OSBB: comparing approaches and the hybrid.
Backup runtime: how many hours the building needs and how to calculate it.
UPS for elevators and pumps: a separate guide on uninterruptible power sources.

Checklist for the board

Before starting a fundraiser for backup power

A list of common loads with priority tiers 0-4 has been prepared.
Nameplate data has been collected for elevators and pumps; missing data is marked as unknown.
The goal has been chosen: rescue, limited operation or full operation of the elevators, and how many hours of backup runtime each tier needs.
It has been determined whether the backup source will feed three-phase motors.
There is an engineer’s conclusion on phase balance and inrush currents.
The location, ventilation, temperature and fire requirements for the room have been discussed separately.
There is a phased implementation plan, not just the most complete option.
The board has verified its own authority under the charter and current legislation.

What the platform does and does not do

Svitlo-Lux helps prepare a list of loads, make a preliminary calculation and set up a public fundraising page. The platform does not sell equipment, does not design the system, does not accept or hold funds and does not guarantee backup runtime. Once the calculation is prepared, the board can register the OSBB and check the fundraiser’s readiness for the next steps.

In this section

Backup power for an OSBB
How an OSBB (condominium association) can approach backup power: roles of the board, engineer and residents, documents, phases and contractor oversight.
Backup power for the elevator
Backup power for an OSBB elevator: rescue mode or full operation, inrush currents, phases, questions for the manufacturer and a worked example.
Backup power for pumps and water supply
How to keep water on upper floors in an outage: pump modes, starting, alternating duty, water reserve and a worked estimate for an OSBB.
Backup power for the boiler room and heating substation
What to power in a boiler room and ITP when the grid is down: circulation pumps, automation, valves. Priorities, a worked example and questions for the engineer.
Emergency lighting in entrances
How to organize emergency lighting for stairwells in an apartment building: self-contained luminaires, a central source, maintenance and testing.
Intercom, internet and fire safety without power
Low-voltage building systems during an outage: intercom, video surveillance, internet nodes, fire alarm. What to check and how to arrange backup.
Generator or inverter for an OSBB
Generator vs inverter with batteries for an apartment building (OSBB, condo association): outage scenarios, starting, noise, fuel, maintenance, hybrids.
Autonomy: how many hours a building needs
How an OSBB chooses backup runtime: formulas with assumptions, a worked example, scenarios by priority tier, margins, temperature and peaks.
UPS for the elevator and pumps
How a double-conversion online UPS differs from an inverter with a battery for an elevator and pumps: bypass, switchover time, inrush current, approvals.

Frequently asked questions

Can an entire apartment building be provided with backup power?: Usually not: apartment consumption belongs to the residents and far exceeds common needs. Common loads are backed up by priority, while apartments are left to the residents’ own decisions.
Where should an OSBB board start?: With a list of common loads with nameplate data and a choice of backup runtime for each priority tier. Only after that does it make sense to compare equipment and request commercial offers.
Is the calculator enough to make a decision?: The calculator gives a range and highlights gaps in the data, but the decision requires an engineering calculation, especially for elevators, pumps, three-phase loads and systems with a generator.

Preliminary backup power calculation Prepare a fundraiser for the OSBB

This material is for general information only and is not a power supply design, legal or financial advice. Calculations are indicative; installation and protection selection must be done by qualified specialists only. The platform does not accept or hold funds.