Beirut , Lebanon

LOS Office Building

The project achieved the LEED Gold certification in 2019. Some climate-friendly features of the building include external vertical shading, PV panels, efficient double-glazing, a high-efficiency VRF system and solar water heaters. A full 3D energy model was conducted to estimate the energy costs reduction compared to an ASHRAE-prescribed baseline scenario resulting in 13.1% energy improvement. LOS has one fully glazed curtain wall on the Eastern façade with efficient double glazing. External vertical shading elements on the western façade with a reduced window-to-wall ratio also help reduce the solar gains. The roof is insulated with 5 cm extruded polystyrene and shaded by photovoltaic panels. A high efficiency VRF system is used for space cooling and heating. solar water heaters are used for domestic hot water and PV panels are also installed.

Project info

Construction phase
New construction
Building type
Non-residential building
Detailed building type
Net floor area
1701 m2
Land plot size
586 m2
4 stories
Construction type
Original construction year of the building
Project contact
Imad Ladkani
Contact email address

Project team

Imad Ladkani
Avedissian & Partners Architects
Energy efficiency consultant(s)
HVAC consultant(s)
Ibrahim Mounayar
Building services
Ibrahim Mounayar

Building Rating and Certifications systems

Rating and certifications systems

Building Envelope

External walls

Description of construction
30cm concrete wall incl. thermal insulation
0.26 W/(m²*K)


Roof type
Flat roof
Description of construction
Concrete slab with 5cm extruded polystyrene insulation
0.52 W/(m²*K)

Openings and windows

Glazing type
Double glazed
U-Value glass
3.3 W/(m²*K)
G-Value glass
Frame material / description
Aluminum frame
Overall u-value window
2.79 W/(m²*K)
Description of construction
Low E double glazing 5, 5, 5

Basement floor

Description of construction
Concrete slab

Technical Building Systems

Ventilation system

Type of ventilation
Mechanical ventilation system without heat recovery

Space cooling system

Primary space cooling system
Centralised chiller │Usually a central system located in the basement
VRV System
Secondary space cooling system
Mounted single-split or window air conditioner│Usually a visible smaller system mounted outside the wall or above the window just supplying one room
DX System for the server room

Space heating system

Primary Space heating system
Air-conditioning system (reversible for heating; air-air heat pump)
VRV System

Water heater system

Primary water heater system
Solar Thermal collector on the roof

Lighting system

Primary lighting system
LED (Light emitting diode lamps)

Shading devices

Type of shading system installed
Static (fix) shading systems as part of the building architecture (e.g. Maschrabiyya, porch roofs, pergolas)
Vertical shades are installed on western facade between windows. They are perpendicular to the façade and protrude 35 cm.


11.52 kWp
Installed on the roof

Final Energy Demand

Energy carrier (1)
Annual heating demand
10 kWh/(m²*a)
Annual cooling demand
15.65 kWh/(m²*a)
Annual lighting demand
14.76 kWh/(m²*a)
Annual hot water demand
4.85 kWh/(m²*a)
Total specific final energy demand
78.88 kWh/(m²*a)

Financial Aspects

Project construction cost
1700000 EUR
Certification costs
3555 EUR
Financing sources
Own + subsidised loan
Financing/funding institution