Frequently Asked Questions

LightStanza for Daylight

LightStanza is used by Architects, Sustainability and High Performance Design Specialists, Daylight Consultants, Lighting Consultants, LEED Consultants, Energy Modelers, and Project Managers. 

Main reasons people choose LightStanza:

  • Individuals who need accurate (Radiance-based) daylight analysis done quickly
  • People looking to explore and compare different daylight products to optimize their daylight designs
  • Experts who want to give feedback and insight more regularly to clients and/or colleagues less experienced in daylight analysis
  • Organizations that need an easy way to create a comprehensive and accurate LEED scorecard that they can benchmark their designs with, iterate on, and submit to the USGBC for credits
  • People who want to be transparent with simulation inputs and outputs about how they arrive at a daylight solution

LightStanza uses the trusted and validated US Department of Energy Radiance Engine. Expert users have control over simulation inputs and the ability to download raw data to verify its results. 

LightStanza provides the fastest Radiance results through its proprietary High Performance cloud server architecture. It highly optimizes server CPU utilization, distributes jobs across multiple servers efficiently, uses fast math libraries to manage copious lighting simulation data, has built in redundancy, and is reliable. It will outperform installed Radiance on a desktop. 

For annual simulations as required by LEEDv4, LightStanza automates Radiance’s most accurate fast 5-phase method. The 5-phase method is designed to work with BSDF data, accurate descriptors of daylight products like skylights, blinds, and redirect films for windows. This method allows you to compute annual daylight availability taking into account human-factors of blind operations. LEEDv4 requires blinds to operate to ensure that occupants can get the real benefit of glare-free light. Users of LightStanza just have to drop in a 3D model and LightStanza will do all the work required about inserting blinds and operating them in accordance to LEEDv4 as well as other control algorithms.

LightStanza offers a 1-click, comprehensive (Option 1 and Option 2), USGBC approved LEED v4 report card. LightStanza rigorously follows the reference IES LM-83 document to assure that your scores will be accepted by the USGBC so you can rely on the output of LightStanza to guide your daylight design. 

LightStanza, unlike any other daylight tools, automatically models blinds which are required for the LEED v4 Spatial Daylight Autonomy part of this calculation. It does so by recognizing windows in any 3D model input format and creating a blind which operates in accordance to LEEDv4 requirements. Most other simulation software is not capable of running annual calculations with blinds since they do not use the 5-phase method or work with BSDF data. Also unique to LightStanza is that you can use your model from Revit, Rhino, SketchUp or ArchiCad as is, without having to simplify or rebuild your model to get it work.

A program that offers more features compromises its ease of use, accuracy, and capabilities. Energy modeling tools force you to use modeling constraints that are specific to them. These tools will force you to simplify and rebuild the design model in ways to make the daylight model less accurate.  This includes creating paper-thin walls, omitting blinds, and removing geometric detail. As a consequence, both quantitative and qualitative lighting calculations are skewed, ending in unrealistic results.  Low quality calculations may under-predict light, geometric omissions over-predict.  LightStanza offers unlimited accuracy and geometric detail. 

If someone offers you a spork it may be convenient, but a spork is not likely to be as capable or useful as having both a spoon and a fork. Tools that sell themselves as a complete energy and daylight analysis tools are making compromises. 

LightStanza is web-based and does not require a plugin. Unlike other building performance tools, it requires no special model building or simplifications to get started. There is a simple 1-button plugin available to upload the model from within Revit, but this is not required for generating results.

Because it’s so easy to run comprehensive LEED v4 calculations in LightStanza, we have customers who have “learned how to do it” by starting to run report cards early in the design process, and by iterating. They have been able to get 3 and even 4 credits (yes, you can get 4)! 

We have people come to us at the end of a design process and it’s frequently too late to achieve the credit– those that iterate early can get daylight right. Developing different types of solar control, adding the right types of skylights and other apertures and, refining material selections are strategies you can test with LightStanza throughout the design process.

Many of the ingredients of high quality daylight are touched upon by LEED– comprehensive climate-based annual analysis, daylight sufficiency, and protection from glare– are part of its Option 1 formula. It will be challenging to find a great solution that does not register in the LEED rubric. 

Nevertheless, LightStanza goes beyond LEED in several ways– false-color renderings, Daylight Glare Probability scores, point-in-time illuminance animations, daylight factor, six different annual daylight metrics, and many more advanced analysis features are available..

Spatial Daylight Autonomy in LEED v4 is defined by the IES LM-83 reference document, which is correlated with empirical studies of what people like in daylit buildings, and it is required for LEED v4 credit. This calculator is a feature LightStanza has gone to great lengths to implement this correctly, and one that is missing from other software.

Renderings are akin to what the eye sees and are the best proxy for daylight quality. Programs that only draw graphs produce an impoverished representation of light. For example, in measuring glare, because the eye is positioned vertically, simply looking at a work plane graph does not tell the whole story.

Yes, LightStanza allows every Radiance parameter to be completely customized for renderings and grid calculations. For example, the following is a partial list of annual metric parameters that can be customized: 

For all annual metrics:

  • Simulation Quality
  • Point Spacing
  • Occupancy
  • Sky Type

For individual metrics:

  • Annual Sunlight Exposure (ASE)
    • Target number of hours
    • Sky type
  • Spatial Daylight Autonomy (sDA)
    • Illuminance target (lux)
    • Time threshold
    • Sky type
    • Blinds
      • Blind control algorithm
      • Blind trigger lux
      • % area trigger lux
  • Continuous Daylight Autonomy (cDA) and Daylight Autonomy (DA)
    • Illuminance target
    • Sky type
    • Blinds
      • Blind control algorithm
      • Blind trigger lux
      • % area trigger lux
  • Useful Daylight Illuminance (UDI)
    • Lower, higher illumination targets
    • Time threshold
    • Sky type
    • Blinds
      • Blind control algorithm
      • Blind trigger lux
      • % area trigger lux
  • Average illuminance
    • Sky type
    • Blinds
      • Blind control algorithm
      • Blind trigger lux
      • % area trigger lux

Calculation Speed: Running LightStanza analysis is like having multiple workstations on your desk, and having a skilled technician figuring out how to distribute each calculation efficiently across machines at every second. In addition, requests can be run in tandem with LightStanza. Hence, as part of your subscription to LightStanza, you are buying hardware and machine-level supervision on demand. 

Maintenance: LightStanza does not require the user to install any software, as it is always up-to-date. PC software requires lengthy installations, constant updates for consistency within the organization, network licenses, and the need to directly edit files on their hard disks to operate. 

Ease of learning and use: As a web-based application with countless R&D hours on user-experience, LightStanza does not require users to learn and debug “expert only” Radiance syntax as well as complex scripts to get to high-quality analysis. This eliminates months of training as well as provides a more reliable workflow. We are often told the speed-up in using LightStanza is not just the cloud compute, but the efficiencies in workflow. 

Flexibility: LightStanza works with models in a variety of formats (Revit, Rhino, SketchUp, IFC), not just Rhino. If your office uses Revit, you can directly import .rvt files into LightStanza. With DIVA for Rhino, you have to convert your drawings to DWG/DXF which homogenize all your model materials. Thus, you will need to spend 10-12 hours reassigning your glass to be glass as well as changing all the surface reflectances before starting any analysis. 

Organizing results: LightStanza keeps a filterable graphical history as well as simulation details for every analysis that is run. Compare this to DIVA or other PC tools that write raw data files without simulation inputs to your hard disk that are nearly impossible to retrieve and decipher as soon as the next day.

There are two general reasons why two of the same simulations do not match exactly: 

1. LightStanza uses Radiance as its engine, which, like other ray-tracing programs, uses monte-carlo ray-tracing; hence there will always be some randomness in the results. To mitigate this problem, run calculations at higher quality settings where variances will be insignificant. 

2. LightStanza frequently releases new versions to give users the most accurate simulations, latest versions of Radiance, new features, latest code compliance scoring updates, optimal workflow, and bug fixes, among other improvements. Thus, a simulation run a year ago may have a different result than a simulation run today. To mitigate this issue, Version numbers are recorded with each simulation in their “Advanced Details”. Additionally, a record of these changes is listed in the “Version History” in the top-right menu of LightStanza.

As a result, we recommend to only comparing data from the same version of LightStanza. If old project data needs to be reviewed and expanded upon, we recommend re-running it to get it up to date. For the most robust way of ensuring you have the correct results will be to re-upload your model to LightStanza.

Yes. Here is how LightStanza keeps your information safe: 

1. Credit Card Information is securely stored with © Stripe. No credit card information is stored locally. To learn about Stripe security, please visit

2. Communications between users and the app are encrypted using SSL (Secure Socket Layers), with a new encryption certificate renewed each year. 

3. All stored files are isolated from the public. Designs, result images, and result data if downloads are “opted in” are stored through Google Cloud. For information about Google Cloud security, please visit

4. When the LightStanza Application is accessed, these steps are taken to prevent users from seeing one another’s data:

  • All sensitive routes of communication in the app are controlled using Access Control Lists (ACL), implemented with standard open source packages and user/team level roles.
  • Permissions are checked again in route-level middleware to limit access to specific database resources – e.g. users must be logged in and can only view designs that belong to their team
  • An enterprise-level application deployment service further protects sensitive data by providing:
    • Authentication (to identify who a user is)
      • No anonymous authorization allowed
      • OpenId Connect Tokens to authenticate users
      • No insecure ports utilized
    • Authorization (to determine what a user is allowed to do)
      • For in-app authorization, see above (ACLs)
      • For other access (e.g. file service and database), LS uses role-based authorization controls. Only LS employees have roles that allow direct access to anything other than the app.
    • Admission Control (to allow a person to modify/change components of the app)
      • Restricted access to all components (e.g. app, database)
      • LS always pulls new software images from a private repository, so credentials are always needed to make changes to the code in any component.

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