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Daylight, simulated before it’s built.

Daylight Lab is a building-physics practice. We model daylight, energy and airflow for architects and engineers. We also build open-source tools that let AI run simulation engines.

Made-up district · 38°N
A made-up district seen from above. Dashed lines show the wind moving along the streets.4.4 M/S4.4 M/SSQUARE 2.4 M/SWINDN
Wind from NWReference 4.0 m/sCorridor 4.4 m/sSquare 2.4 m/s

Turn the wind. Streets that line up with it carry more air.

Illustrative, not a simulation.

Buildings use about 40% of the world’s energy. Much of it goes on lighting, heating and cooling that a better design would not need.

The problem

Design teams decide window sizes, shading and room depths early, often by rule of thumb. Those choices fix a building’s energy use and comfort for decades.

How we help

We test those choices with physics-based simulation while they are still cheap to change. You get clear numbers, plots and a recommendation you can act on.

What the district shows

  • Wind

    Buildings use about 40% of the world’s energy.

    It starts with the city: green corridors let the wind cool the streets.

    CFD & microclimate
  • Outdoor comfort · UTCI

    On the street, shade decides how hot it feels.

    We map the felt temperature where people walk and wait.

    CFD & microclimate
  • Shading · Solar gain

    Shading blocks the high summer sun.

    Louvres keep it off the glass, and still let the low winter sun in.

    Building energy
  • Illuminance · Visual comfort

    Inside, we measure the light people work in.

    We map how far daylight reaches, and when the sun causes glare.

    Daylight & lighting

What we do

Simulation studies for new buildings and retrofits, from concept to certification.

  • Daylight & lighting

    Climate-based daylight modelling, daylight factor, sDA and ASE, glare and EN 17037 checks. Artificial lighting layouts and controls.

    Radiance, Daysim, ClimateStudio, DIALux, Relux

  • Human-centric lighting

    Spectral simulation of melanopic EDI and alpha-opic metrics to CIE S 026, balanced against glare and energy use.

    Lark Spectral, Radiance

  • Building energy

    Whole-building energy models to compare design options, plan retrofits and show nZEB or code compliance.

    EnergyPlus, OpenStudio, DesignBuilder, Honeybee (Ladybug Tools)

  • CFD & microclimate

    Indoor airflow, ventilation and heat transfer. Outdoor comfort in streets, squares and courtyards.

    OpenFOAM, ENVI-met, SimScale

  • Certification evidence

    Daylight, views and lighting calculations for LEED, WELL, BREEAM and DGNB, documented for submission.

    LEED, WELL, BREEAM, DGNB

  • Teaching & workshops

    Postgraduate teaching and hands-on training for design teams in lighting measurement and simulation.

    Hellenic Open University

  • Custom AI solutions

    We integrate custom AI solutions into your workflows. AI assistants connect to the simulation tools you already use, so they can set up models, run studies and draft reports.

    Anthropic (Claude), OpenAI (ChatGPT), Google (Gemini), MCP, Skills, Python

How a study runs

  1. 01

    Brief and model

    We agree the questions, metrics and standard. Then we build the model from your drawings.

  2. 02

    Simulate

    We run the simulations and test the design options you care about, side by side.

  3. 03

    Report

    You get plots, numbers and a clear recommendation. We stay on call as the design changes.

Try it: the sun over Athens

Pick a day and an hour. See where the sun sits over Syntagma Square, and where the shadows of the real buildings fall.

The map uses the sun-path chart that designers read every day. Rings show the sun’s height. Curves show its path on the 21st of each month. Dotted lines mark the solar hours.

Syntagma, Athens · 37.98°N 23.73°E

Buildings © OpenStreetMap contributors. Some heights are estimated.

21 Jun 13:27 Athens time 12:00 solar Altitude — Azimuth — Sunrise — Sunset —

Drag the sun along its path, or use the sliders. Shadows fall from the real buildings around Syntagma Square.

A side-lit room, cut away. Daylight enters through the window and fades with depth. The floor splits into a primary daylight zone, a secondary daylight zone and an electric lighting zone. A dashed reference plane runs at desk height, 0.8 m.06091518LAMP 0 %LAMP 52 %LAMP 74 %12:000 M3 M6 M9 MDISTANCE FROM FAÇADEPRIMARYDAYLIGHT ZONESECONDARYDAYLIGHT ZONEELECTRICLIGHTING ZONEREFERENCE PLANE 0.8 MWINDOWDAYLIGHT
Time 12:00 Lamp output: Primary — Secondary — Electric —

Move the sun, or play a day. With daylight-linked control, each lamp dims when its zone has enough daylight.

Daylight zones in a side-lit room. Illustrative, not a simulation.

Open source

Simulation tools an AI can drive.

Our MCP servers let assistants such as Claude run Radiance on your own models. Your model stays on your machine.

Every window is an energy decision.

Daylight reaches further.

Well-designed façades carry sunlight beyond the usual daylit zone of deep offices. Good design lights more of the floor than rules of thumb suggest.

Light changes the energy balance.

More daylight cuts lighting energy but can raise cooling loads. We simulate both together, with climate-based models.

People are not light meters.

Light sets our body clock. We measure melanopic light and glare, not only lux on a desk.

Latest from the lab

All repositories on GitHub
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Research and selected work

Current research, 2026–2029

EYEXIA: lighting for wellbeing indoors

A Hellenic Open University project on human-centric lighting. We run high-resolution spectral simulations to quantify melanopic EDI, and balance it against glare, vertical illuminance and energy use under WELL, LEED, BREEAM and DGNB.

Journal papers

  • 2020Examining the impact of daylighting and the corresponding lighting controls to the users of office buildings. Energies
  • 2019Minimizing energy for artificial lighting in a Hellenic public school classroom, aiming for nZEB. Energy and Buildings
  • 2018A review of light shelf designs for daylit environments. Sustainability
  • 2017An active sunlight redirection system for daylight enhancement beyond the perimeter zone. Building and Environment
  • 2017Harvesting daylight with LED or T5 fluorescent lamps? The role of dimming. Energy and Buildings

Selected projects

  • 2023Heat transfer CFD for the restoration of the Electric Power Station building, Lavrion Technological and Cultural Park.
  • 2022Citation, architectural competition for the renovation of Eleftheria Square, Kavala.
  • 2015Daylight assessment of exhibition spaces, Museum of Modern Art Basil and Elise Goulandris.
  • 2014Building energy performance analysis, Department of Biological Sciences, University of Cyprus.
  • 2012Artificial lighting analysis of commercial bank branches.

Dr Antonios Kontadakis

Mechanical engineer with a PhD in daylighting and more than 15 years in sustainable building design, energy simulation and emissions reduction.

I teach building lighting measurement and analysis on the postgraduate Sustainable Interior Design programme at the Hellenic Open University. I lead emission reduction work in the gas distribution sector. Daylight Lab is where I take on simulation studies and publish open-source tools.

PhD
Daylighting systems, University of Thessaly, 2021
MSc
Energy, Heriot-Watt University, 2012
Dipl.
Mechanical engineering, University of Western Macedonia, 2008
Teaching
Hellenic Open University, since 2023
Fellowship
IKY / Siemens fellowship of excellence, 2017

Have a building in mind?

Send drawings or a short description. We reply within two working days with questions and a fee estimate.