Multi-tenant Commercial Building




Located in the center of Lyon, a city abundant
with historical architecture, this building was
built at the end of the 19th century. Today it
houses a multi-tenant operation—home
to several offices and retail outlets.
When the time came to replace the existing
HVAC installation, care and preservation of the
architecture was integral. With its compact floor
footprint, SET FREE Σ was selected, enabling
a 100% indoor installation with no significant
retrofit works needed. This kept the integrity
of the historical building intact.


Key outcomes
✓ Compliance with Regulations — A non-invasive installation with
zero reconstruction was achieved, keeping the visual and historical
integrity of the architecture.
✓ Respecting the Neighborhood — Acoustic specialists worked to
ensure there was zero noise pollution to the surrounding
historical neighborhood.
✓ Improved Installation — Outdoor equipment was no longer installed
outside as it was previously, instead it was cleverly concealed
within the attic.
✓ Tenant Benefits — Each tenant now receives individualized and
accurate billing, reflecting their actual usage of the air conditioning.
✓ Customized Comfort — With simultaneous cooling and heating
options permitted during autumn and spring, each tenant
can now satisfy their own specific needs.

Issues to be addressed
• The previous HVAC system in this building consisted of a hydraulic system which was
heated by a gas boiler in winter and cooled by chiller units, located on the roof, in summer.
Not only did this system disrupt the urban architectural landscape, it was also aging,
facing significant water leakage and resulting in high maintenance costs.
• During autumn and spring, tenants’ cooling and heating needs were conflicting. Due
to the nature of their different businesses and varying exposures to sunlight in the
building, some tenants required cooling while others desired heating to achieve comfort.

Key stakeholder requirements
SET FREE Σ system addressed all stakeholder requirements.
• Tenants — required the ability to pay for only the energy they consume—no more, no less.
• Building Owner — required a low installation cost and to avoid retrofitting of the
existing layout.
• Local Urban Authorities — required equipment to be installed indoors, as outdoor
installations are prohibited for classified historical monuments. Additionally, it was
specified that the air conditioning was to add no more than 3dB to the pre-existing
ambient noise level in the neighborhood.
• HVAC System Designer — wished to install the outdoor equipment in the attic which
was previously unused, converting it into a technical room and providing easy access
to an ambient air source.

Our solution
After analysis of the building constraints and requirements, SET FREE Σ
was found to be the only suitable system available on the market:
• Compact Floor Footprint — The small width of the 18HP and 24HP outdoor units
(1,219mm and 1,609mm) made SET FREE Σ the only solution on the market small
enough to fit within the limited floor space in the building attic. Without SET FREE Σ
outdoor units, this whole retrofit project would not have been possible.
• Reduction to Outdoor Noise — To prevent noise pollution in the surrounding historical
neighborhood, acoustic specialists integrated noise reduction equipment with the louvers
of the ambient air inlets and outlets. This created a new challenge, affecting access to
outdoor air. To solve this, the external static of the SET FREE Σ outdoor units was set up
at 80Pa. This solution allowed for sufficient heat exchange and preserved performance.
• Flexible Piping — Due to the building’s layout, a distance of 50m between the first
multi-branch kit and the furthest indoor unit was required. SET FREE Σ could easily
accommodate this, with a capability of up to 90m distance between the two.
• Back-up Operation — In case of failure in one module of an outdoor unit, SET FREE Σ
has a back-up system which automatically kicks in to operate the remaining modules,
giving building owners reassurance.
• Centralized Monitoring — Through the use of CS-Net Web, the building owner is able to
monitor the entire SET FREE Σ installation from a remote computer. The building owner
can also visualize each tenant’s total energy consumption, enabling accurate invoicing.



A multi-tenant commercial building

Lyon, France

Retrofitting an 8-storey office building

Date of installation


Outdoor Units

Heat Recovery Type
Total Capacity: 106HP
• Floors 1, 2, 3:
• Floors 4, 5:
• Floors 6, 7:
28HP–1x16HP 1x12HP

Single-port + multi-ports

Indoor Units
Office Area
79 x Ducted units

1st Floor Shops
water modules

Other Spaces
3 x Wall-mounted units


Central Station
CS-NET Manager