Main and Secondary Usable Space: Differences and Impacts on Commercial Real Estate

When renting commercial real estate, you will inevitably come across the terms main and secondary usable space. This distinction is not just a technical subtlety, but has a direct impact on your rental price, ancillary costs, and the actual usability of your premises. Main usable spaces are the areas where your core business takes place – such as office spaces or sales areas. Secondary usable spaces include supporting areas like storage rooms, sanitary facilities, or technical rooms. In this article, you will learn how these space types are defined, why the distinction is crucial for your cost planning, and what you should pay attention to in lease agreements.

What are main and secondary usable spaces?

The distinction between main and secondary usable spaces is based on the Swiss standard SIA 416, which systematically classifies spatial areas in buildings. This standard helps landlords and tenants create transparency regarding the actual usability of spaces.

The main usable space (HNF) includes all rooms used for a company's main activity. These include:

Office spaces and workplaces
Sales and retail spaces
Production and workshop areas
Meeting and conference rooms
Showrooms and exhibition areas

The secondary usable space (NNF), on the other hand, encompasses all supporting areas necessary for operations but not directly serving the main activity:

Sanitary and toilet facilities
Storage and archive rooms
Technical rooms (heating, ventilation, server)
Cleaning and utility rooms
Kitchenettes and small break rooms

Important to know: Circulation areas such as stairwells, corridors, or elevators are treated separately as their own category and do not count as either main or secondary usable space.

Space efficiency: Why the distinction is important

Space efficiency describes the ratio between the usable main space and the total area of a property. The higher the proportion of main usable space, the more efficiently you can use the property for your core business.

When viewing commercial spaces, you should not only pay attention to the total square meters but specifically ask: How much of it is actually available as main usable space? An office with a total area of 200 m² can have very different proportions of usable office space depending on the building's structure.

Example calculation for space efficiency

Let's take two office spaces, each with a total area of 200 m²:

Property A:

Main usable space: 160 m²
Secondary usable space: 25 m²
Circulation space: 15 m²
Space efficiency: 80%

Property B:

Main usable space: 130 m²
Secondary usable space: 35 m²
Circulation space: 35 m²
Space efficiency: 65%

Although both properties are the same size, Property A offers significantly more usable workspace. Especially in high-price locations like Zurich or Geneva, this difference can have significant financial implications.

Rental price logic: How main and secondary usage affect the price

In Switzerland, the rental price for commercial real estate is usually quoted per square meter and year. But which exact area is calculated? There are different approaches here that you should definitely clarify in the lease agreement.

Different calculation models

1. Pure main usable space: Some landlords calculate the rent exclusively based on the main usable space. Secondary usable spaces are either included free of charge or billed at a reduced square meter price.

2. Total usable space: More common is the calculation based on the total usable space (main plus secondary usable space). Here you pay the same square meter price for all used rooms.

3. Tiered prices: Some landlords differentiate and charge a higher price per square meter for main usable spaces and a lower price for secondary usable spaces.

A concrete example: With a rental price of CHF 350/m²/year and 160 m² of main usable space plus 25 m² of secondary usable space, the result is:

Variant 1 (only HNF): CHF 56,000/year
Variant 2 (HNF + NNF): CHF 64,750/year
Variant 3 (HNF CHF 350, NNF CHF 200): CHF 61,000/year

The difference can therefore amount to several thousand francs per year. Make sure that the lease agreement clearly defines which spaces are calculated and how.

Distribution of ancillary costs for main and secondary usable spaces

In addition to the rent, commercial real estate also incurs ancillary costs on account. These typically include heating, water, cleaning, caretaking, and building maintenance. The distribution of these costs is often based on the used space.

Understanding the distribution key

For properties with multiple tenants, ancillary costs are divided according to a distribution key. This is usually based on the ratio of your usable space to the total area of the building. The question arises: Are only main usable spaces included in the calculation, or secondary usable spaces as well?

An example: In a building with 1,000 m² of total usable space, you rent 185 m² (160 m² HNF + 25 m² NNF). The annual ancillary costs are CHF 50,000.

If all spaces are included: Your share = 18.5% = CHF 9,250
If only main usable spaces: Your share could be correspondingly different

Check the lease agreement carefully to see how the distribution of ancillary costs is regulated. According to Swiss tenancy law (CO Art. 257a), only costs actually incurred may be passed on, and the distribution key must be comprehensible.

Special secondary usable spaces with extra costs

Some secondary usable spaces cause above-average costs. A server room with air conditioning or a warehouse with separate heating can cause significantly higher energy costs than a normal office. In such cases, the lease agreement should provide for separate billing or an adjusted distribution key.

Practical tips for renting commercial spaces

To ensure you don't experience any nasty surprises when renting commercial spaces, we have put together some practical recommendations for you:

1. Request a floor plan

Ask the landlord for a detailed floor plan according to SIA 416, which clearly shows the main and secondary usable spaces. This creates transparency and avoids later discussions.

2. Check the lease agreement precisely

Ensure that the following points are clearly regulated in the lease agreement:

Which spaces are rented at what price?
How are ancillary costs distributed?
Which spaces are for exclusive use, and which are communal?

3. Realistically assess your own needs

Think carefully about how much main and secondary usable space you actually need. A spacious warehouse is essential for an e-commerce company, but may be superfluous for an advertising agency.

4. Ensure comparability

When comparing several properties, make sure that the area details were recorded according to the same standard. Only then can you meaningfully compare rental prices.

5. Flexibility for the future

Consider whether you can or want to convert secondary usable spaces into main usable spaces later. For growing companies, it can make sense to convert a former warehouse into additional office space – provided the landlord agrees.

Conclusion: The right space for your business

The distinction between main and secondary usable space is more than just a technical formality. It has a direct impact on your rental costs, space efficiency, and ancillary cost settlement. A clear understanding of these space categories helps you make informed decisions and find the right commercial property for your company.

When looking for real estate, do not only pay attention to the total size, but analyze the space allocation in detail. Request plans according to SIA 416 and clarify precisely in the lease agreement which spaces are calculated and how. This ensures that you get the optimal usable space for your money and that no unexpected costs arise later.

For complex properties or larger rental spaces, it is worth bringing in a real estate expert or lawyer to review the lease agreement. Especially with long-term tenancies, this investment often pays off.

Disclaimer: This article is for informational purposes and does not replace professional legal or real estate advice. For specific questions regarding your lease agreement or area calculation, we recommend consulting an expert.