The LAMILUX Primer


Great daylighting is fundamental to high-performance green buildings, and nothing puts a cherry on top of a great space like a skylight. The complication is that roof glazing is the keystone in your continuous red line, and a misstep on that skylight can unravel the thoughtful planning you put into the rest of the building. Potential for thermal bridging, overheating, cold air convective currents and air or water leaks can damping your joy or destroy the gains of free daylight and visual comfort. That’s why finding the right fit for the job is well worth the effort.

LAMILUX has been in the business of skylights since 1955, and has a solid background of experience and respect in the field. Given that fact, it’s no surprise that the LAMILUX-CI System was the first Passive House Certified daylight system on the market and is part of LAMILUX's passivhaus product range (glassroofs, skylights, exit hatches).

The LAMILUX –CI System of skylights and flatroof windows offers top notch energy-efficient German engineering and manufacturing, including the LAMILUX FE Energysave: certified class ph-A skylight by the Passive House Institute (PHI). This skylight collection is customizable to your project’s specific needs, with all basics you should expect from a high-efficiency, triple-glazed fenestration already built in, and a wide range of additional features to choose from (shading, motorized operation, rain- and wind-sensors, etc).


Each of these models undergo rigorous engineering and testing to ensure they prevent condensation and mold growth. In situations where the outside temperature is 23°F with an inside temperature above 68°F and 50% relative humidity, the 54.7°F isothermal line must remain continuous within the components of the skylight assembly. The diagrams below show how each model fared during these tests.

There are four types of LAMILUX skylights 475 currently has to offer:

  1. LAMILUX FE Energysave
  3. LAMILUX Exit Hatch FE
  4. LAMILUX PR60 flatroof windows/curtainwalls

LAMILUX FE Energysave

If you're looking for state-of-the-art, best-in-class: this is your pick. The LAMILUX FE Energysave has been tested and certified to be a ph-A "Advanced Component" by the Passive House Institute in Darmstadt. It has an argon-filled triple pane, and the frame is EPS insulated with an aluminum finish. The curb - made from rigid polyurethane foam - is almost 16" high, so it can be overinsulated. The whole assembly is completely thermal-bridge-free and comes in any size you want from 24" square to 71" square. Here are some of its impressive stats:

lamilux section 2

  • Installed U-factor: 0.148 BTU/hr ft2°F (0.84 W/m2K)
  • U-glass: 0.105 BTU/hr ft2°F (0.6 W/m2K)* 6-12-4-12-8mm (42mm thick)
  • U-frame: 0.107 BTU/hr ft2°F (0.61 W/m2K)
  • Frame width 4.6" (116.4mm)
  • Solar Heat Gain Coefficient options of 0.49 and 0.32 by request
  • Visual Transmittance up to 0.69
  • ACS plus superspacer - Ψg - 0.017 BTU/hr ft°F (0.029 W/m2K)

  • Highest airsealing class - 4 (DIN EN 12207)


  • fRsi=0.73

  • Curb height 15.75" (400mm) allows for 9.5" - 13.4" of over insulation of the curb. Improving the Ψ install to as low as 0.044 BTU/hr ft°F (0.076 W/mK)


If your budget calls for a lower upfront cost, the LAMILUX FE may be the way to go.


It contains many of the features with the same craftsmanship found in the Energysave, but not at the boundary-pushing performance level needed for full PHI Certification. Again, you have triple-pane, argon-filled glass. CFC-free.Most importantly for your thermal envelope it's thermal-bridge-free, with the continuous isothermal line maintained throughout. The lighter frame still packs a punch, performing at a range of technical specifications based on your request:U-glass: 0.105 BTU/hr ft2°F (0.6 W/m2K)

  • U-glass: 0.105 BTU/hr ft2°F (0.60 W/m2K) - triple*
  • U-frame: 0.145 BTU/hr ft2°F (0.82 W/m2K)
  • Frame width 4.6" (116.4mm)
  • Solar Heat Gain Coefficient: 0.47-0.32
  • Visual Transmittance up to 0.69
  • tripleisotherm

    Chromatech Ultra spacer Ψg - 0.029 BTU/hr ft°F (0.0504 W/m2K)

  • Airsealing class - 3 (DIN EN 12207)

  • Minimum curb height 5.9" (150mm) allows for some over insulation to improve Ψ instal.


The LAMILUX Exit Hatch FE is a variation on the FE described above that is fully openable to provide roof access or for ventilation. Two options are available:

Pneumatic spring system


  • With triple glazing, size up from 35.4" to 39.3" (900mm to 1200mm both square and rectangular)

Horizontal, slide-open roof exit hatch

  • Operated using two external, synchronised 24 V rack-and-pinion drives
  • Up to 39.3" x 59" (900mm x 1500mm)
  • Safety contact rail protects against injury when hatch closes

Roof hatch comfort - double leaves, for over stairways

  • Two electric motors attached to the external corner section
  • Four-layer seal system
  • Size 47.2" x 118.1" (1200x3000mm) w. 16" (400mm) curb

LAMILUX roof exit comfort

Head clearance needs to be taken into account when the client is planning and building the stairway.

All the roof exits can be used for night time flushing (cooling) during hot days/cool summer nights.

The Curbs

LAMILUX uses fibre-reinforced composites for the upstands, which are CFC-free. Solid white in color and thermally insulated with polyurethane hard foam. They can be over insulated to optimize the thermal performance of the roof and skylight interface. The curbs have a 3-5 degree pitch, which assures the flatroof window waterproofing.

PR60 flatroof windows

Marriott Hotel am Potsdamer Platz

Thermally broken horizontal "curtainwalls", have a similar CI (continous insulation) system built in and can be made in PHI-certified or high performance versions, to light your larger public spaces. More information in the PR60 product brochure or on 475 Daylighting site.

The Perks


  • Fixed or crank roof hatch opening standard
  • Optional motorized spindle (FE) or concealed chain drive FE Engerysave
  • Aluminum shade with leave pattern (removable for winter) - see below
  • Motorized external shade to protect against overheating on sunny summer days

alu Lamilux flatroof shade

Fully automatic features allow you to open up to let in fresh air, or cover up with the lower the shade. The automatic shade action makes you feel a little like you’re in a convertible (complete with soothing music):

A smart skylight puts the finishing touch on a smart building. Come by our Brooklyn showroom to see an FE Energysave with all the bells and whistles or contact us for more information or to place an order.

* Uglass values are for vertical oriented glass. The effective Ug for horizontal glass in each window can be calculated to be increased to:

  • FE Energysave - U-glass effective: 0.147 BTU/hr ft2°F (0.84 W/m2K)
  • FE - U-glass effective: 0.159 BTU/hr ft2°F (0.90 W/m2K)

Related Blog Posts:

Continue the conversation on social media