Israeli Standard (SI) 5281: The Practical Guide to a Green Upgrade of an Existing Office Building

In recent years, office-building owners get the same question from three directions at once: corporate tenants ask about the building's environmental performance before signing a lease, banks and institutional bodies request ESG data before financing or purchase, and property managers try to understand what can be done in an occupied, operating building — without evicting tenants and without an extensive renovation. At the center of all this stands Israeli Standard (SI) 5281 — the standard for sustainable building. The common difficulty: most of it was written with new construction in mind, and the first feeling of anyone holding an existing building is that the door is locked in their face. It isn't. Most of the way can be traveled in an existing, occupied building — if you know where to begin.

What SI 5281 is and why it applies to an existing building too

Israeli Standard (SI) 5281 is the standard for sustainable building (green building) published by the Standards Institution of Israel. It defines a system of requirements and scoring across several areas — energy, water, materials, indoor environmental quality and building management — by which a building receives a rating. Most of the public discussion deals with new projects, because there it's easier to plan green from the very first stage. But from an existing property owner's perspective, the real question isn't whether the building was built to SI 5281, but whether it is managed today in a way that allows it to be measured, improved, and to present reliable data.

This distinction is critical. A corporate tenant reporting ESG to its global headquarters isn't necessarily asking for a framed green-building certificate — it's asking for energy-consumption data relative to area, a documented waste policy, and confirmations that the building is managed with environmental responsibility. Most of these can be supplied in an existing building long before you talk about a formal certificate. The business value starts in management, not in a stamp.

An existing building doesn't need to become green in a single day. It needs to start being measured. Once there's measurement — there's improvement, and once there's documented improvement — there's an ESG story you can present to a tenant and a bank.

What actually happens in the field: the pressure that comes from tenants

Many existing buildings in Israel discover the ESG topic not out of their own initiative, but the moment a large corporate tenant arrives and presents requirements. In practice it looks like this: the organization's procurement department sends a "sustainability questionnaire" with dozens of questions — how many kilowatt-hours per area, is there monitoring?, what's the waste policy?, is there building control?

Whoever doesn't manage ongoing data discovers they have nothing to answer. Not because the building is bad — but because it wasn't measured and wasn't documented. This is the point where orderly management becomes a real competitive advantage: a building that can open an ESG file for a tenant within days will close a deal that a building without data will lose.

First stage: measure before you improve

The most common mistake is to jump straight to replacing equipment — swapping lighting fixtures, buying a new AC — without knowing what consumes what. In a typical office building, a large share of consumption hides in systems no one looks at: central HVAC running unnecessary hours, pumps running at a constant load regardless of demand, lighting in shared areas that stays on around the clock, and backup systems wasting in the background.

Before any investment, a baseline picture of consumption is required. That means aggregating the whole building's electricity data, breaking it down as much as possible by systems and areas, and identifying the big consumers. This picture is almost always surprising — it shows where the energy really escapes, and not infrequently points to waste that can be fixed by a setting alone, not by a purchase.

What a practical baseline mapping includes

• Breaking down consumption: HVAC, lighting, elevators, pumps and service systems — who consumes how much and at what hours.
• An hourly profile: when the building peaks, and what it consumes during the hours it should be empty.
• Consumption relative to area: normalizing consumption by the leased area — the metric corporate tenants look at.
• Self-comparison: month-over-month and season-over-season trends, to see whether the improvement actually happened.

Without a baseline picture, every improvement is a gamble. With a baseline picture you can aim the investment at the place where it pays back fastest.

Energy efficiency in systems — what's applicable in an occupied building

The good news for an existing building owner: a considerable part of the energy improvement doesn't require renovation, but rather proper management of what already exists. Below is the logical order — from cheap and quick to expensive and complex.

1. Tuning and proper operation — almost no investment

• Matching the operating hours of HVAC and lighting to the actual occupancy schedule — not leaving systems on "just in case" outside working hours.
• Setting sensible, fixed target temperatures, and preventing "thermostat wars" between floors that double the HVAC load.
• Checking the state of the filters, heat exchangers and schedules — a neglected system consumes far more for the same output.
• Closing doors and windows on floors with active HVAC — sounds trivial, but in practice produces measurable savings.

2. Focused upgrades — an investment that pays back quickly

• Switching to LED lighting in the shared areas and the parking garage, with occupancy sensors and Shabbat/holiday timers.
• Variable-frequency drives (VFDs) for pumps and fans — they operate by demand rather than always at full load.
• Focused sealing and insulation improvements in the envelope and technical spaces, where clear energy losses are found.

3. Smart control and operation — a planned investment

• A Building Management System (BMS) that schedules systems by occupancy and by weather conditions.
• Connecting sub-meters to a monitoring system, to see consumption in real time — not just on the bill at the end of the month.

The order matters: most buildings achieve significant savings already at the first, cheap stage, before spending a shekel on equipment. Whoever skips straight to purchasing pays twice — once for the equipment, and once for the system still being operated incorrectly.

Consumption monitoring — what you can't see you can't manage

Monitoring is the heart of any real ESG move in an existing building. The difference between a building that "tries to save" and one that "manages its consumption" is the ability to see data on an ongoing basis — not in retrospect. The electricity bill at the end of the month tells you how much you consumed, but not when, where and why. By the time you discover a fault through the bill, it's already been running for weeks.

Practical monitoring in an existing building is built in layers: main meters at the building level, sub-meters by systems or areas, and sometimes measurement at the tenant level. When the data is aggregated in one place, you start to see phenomena you couldn't detect otherwise — a system running at night, a consumer that suddenly spiked, or a floor consuming abnormally relative to the others. Each of these is waste that can be stopped, and sometimes also an early sign of a technical fault.

This is the point where orderly operational management makes the difference: when the monitoring is connected to a system that also manages preventive maintenance and service requests, a consumption anomaly automatically becomes a task — someone checks, fixes and documents — instead of staying a number on a screen no one acts on. At Domera the monitoring and the maintenance sit in the same system for exactly this reason: a data point without an action is worthless.

Waste policy — the easy win everyone forgets

If energy efficiency is the expensive move, a waste policy is the cheap win. It requires mainly organization, procedures and documentation — not costly equipment — and it's one of the components easiest to present to a corporate tenant, because it's visible. A tenant who visits the building and sees an orderly separation setup understands immediately that this is responsible management.

What builds a worthy waste policy

• Source separation: separation points for paper, cardboard, plastic and packaging — in the shared areas and near the tenants.
• Dedicated streams: orderly handling of electronic waste, batteries and lighting fixtures — not disposal in the general bin.
• Disposal documentation: receipts from the disposal contractor — what is disposed of, where, and at what frequency. Exactly what's needed for ESG reporting.
• Construction waste: a procedure for handling waste from tenant renovations, which is usually managed without oversight.
• Communication to tenants: clear signage and instructions — a policy no one knows about doesn't actually exist.

The great advantage of a waste policy is that it's documented by its nature: every disposal generates a receipt, and every receipt is a layer in the building's ESG file. Within a single season you can go from "we have no data" to "here's an orderly waste report."

What's immediately applicable, what requires planning — an orientation table

Not every move is at the same level of effort. The following table sorts the main steps by time horizon and investment, so you can build a realistic plan instead of a wish list.

The principle: start from the top rows. They're cheap, fast, generate data and results — and justify the heavier integrations later.

What about a formal certificate? When it's worth examining

A question that comes up a lot: "Do we need to apply for a formal green-building certificate under 5281?" The honest answer: for most existing buildings — not at the first stage. Here's why:

• Certification cost: applying for a formal certificate requires certified guidance, tests, documentation and fees — a cost usually not justified if the building isn't yet managing ongoing data.
• Planning requirements: some of the standard's requirements relate to the design and construction stage and aren't applicable retroactively.
• The value is already available without it: tenants and banks readily accept documented management and operational data — even without a formal stamp.

When is it worth considering certification? When an orderly data infrastructure already exists, when there's a comprehensive upgrade plan, and when the building is competing for global or institutional tenants who explicitly require it. The practical recommendation: start from management and measurement, and consider formal certification when the data is already there.

Checklist: where your building stands today

Before planning an upgrade, it's worth going over this list and honestly marking what already exists. Every "no" is a quick opportunity for improvement.

• Do I have a baseline picture of the building's energy consumption, broken down by systems?
• Do I know what the building consumes during the hours it should be empty?
• Do the operating hours of HVAC and lighting match the actual occupancy, or were they set "just in case"?
• Have the shared areas and the garage switched to LED with occupancy sensors?
• Is there a written waste-separation policy, with separation points and signage for tenants?
• Are there documented disposal receipts that can be presented in a report?
• Does a consumption anomaly or a system fault generate a task someone handles — or does it stay a number on a screen?
• If a corporate tenant or a bank asked me tomorrow for basic ESG data — do I have somewhere to pull it from?

If most of the answers are "no" — that's not a failure. It's the starting point of most existing buildings in Israel. The gap between a managed building and an unmanaged one, in ESG terms, is exactly this list.

Why this is a matter of ongoing management, not a one-time project

The great temptation is to treat ESG and SI 5281 as a project: hire a consultant, make one big move, produce a report and go back to routine. But ESG isn't an event — it's a way of managing. A building that made an impressive upgrade and then went back to operating systems incorrectly will lose the achievement within a season. By contrast, a building that manages its consumption, its maintenance and its waste on an ongoing, documented basis will improve year over year — and will always have a data file ready for a tenant, a bank or a due-diligence review.

That's the difference you see in the field. When consumption monitoring, preventive maintenance, service requests and documents sit in one management system, ESG stops being a chore you wake up to right before a tenant's request, and becomes a natural product of proper management. Every month generates data, every data point generates an action, and every action is documented.

At Domera we manage a real office building on exactly this principle — monitoring, maintenance and documentation in the same system. Want to see where your building stands and where to begin? Get a starting review.