Are we talking about one skylight or multiple skylights? Not sure if it is the best fit here based on skylight types included, but a tool like skycalc can help you calculate the savings/penalty for lighting, cooling, and heating. There is a slight learning curve to get reliable results if you haven't used it yet.

Ramana thank you I will look for this, we are looking at projects with many skylights already built and we are looking for a simple reference to reduce the numbers and area of skylights in future for design in production.

Thank you William I am looking for a short answer, a rough estimate I will read through your links. We are engaged in EVE studies and for benchmarking real estate such as large shopping centres [www.solideagroup.com]. We do this in the buying period or on handover such as after completion or warranty every asset manager is keen to make sure their benchmark beat the pier average.

We would like to give a simple impact study so we can prioritize for example a solar shading device over an air tightness workout. Our clients are usually large funds and they want to roll our EVE over a number of years, in a road plant

K values are circa 2,2 max in CE and if the skylight is fully glazed the performance can be slightly better. We can forget about the solar shading capability its almost always foils nowadays which fail almost instantly. In the case of [possibly] air tight smoke hatches of a few m2 the class is much lower e.g. K = 2,5 max

I wondering how we can estimate the value of priority the easiest

Welcome to email me about this subject I am going to write an article very soon [email protected]

Thank You William I will

Dear Steve,

As an independent researcher, I recommend you to use DesignBuilder software package to build your skylight (or any building block). Then you can simulate solar gain and energy consumption of all building blocks (Also skylight) versus the time. I did use it and had a interesting result.

http://www.designbuilder.co.uk/

Best wishes

Maysam thanks for your comments

Unfortunately we deal with as-built assets, so we have now collected a massive amount of data on kWh/m2 on retail centres with a reasonable critical mass each time measuring the skylight area and then taking a view of the solar penetration we have equipment to measure UVA and UVB inside the shopping destination at any time

Now we took delivery of and OPTRIS active IR Camera we are building a Drone with Pix4D Software and we can build a 3D IR model with the least surveying time imaginable  - take a look at my conference room table 

I wish the best for you. 

Thank You Maysam, I wish you all the best too