 Hey, welcome to lesson on lighting Let me tell you this. This is the most interesting chapter Interesting, I would say the material that you would be learning and using in your life in our country as a homeowner We can do a lot in terms of savings for lighting lighting costs In this chapter, we are basically going to look at the basic lighting principles and definitions lighting principles is you know light can be generated in several ways and We are going to look at the ways in which we can generate light and which is the most efficient one of all these methods And we will also learn a little bit about you know some of the definitions like you know how light is measured and what is the intensity Light intensity and how do we measure the efficacy or efficiency of lighting and so on and so forth And we will also look at the different types of bulbs that are available around us to use actually most commonly we use incandescent bulb and Some of you are familiar with fluorescent bulbs and there are high-dent Intensity discharge lamps and all and we will be looking at how each of these types basically work and Also, how the light is generated. What is the efficiency of our with which we generate lighting? and As far as calculations are concerned We will be doing the most important calculation in this chapter that is again life cycle analysis life cycle analysis is As I mentioned in the last chapter it is the total cost over its life cycle life cycle is the moment you buy Until the moment it dies or basically it's it's put to retirement Until then what would it cost in other words the cost would be to buy it and To feed it the electricity or the energy and then if there are any maintenance costs, they're also involved so we have to calculate all these aspects over the lifetime of a particular bulb and Then compare bulb a with bulb B So that life cycle analysis is what you will have to spend Quite a bit of time and make sure that you understand this in this chapter and the way we measure the efficiency efficacy of lighting and Improved lighting controls if we have an existing home or existing system What can we add? How we can improve the efficiency how we can get more light for less energy? So this is a chapter where really in our country. We can almost save about 50% of our energy and we spend about Almost 40 billion dollars a year in this country on lighting so easily our country can save about 20 billion dollars and associated energy that is involved and the impact think about it impact That we can make by using more efficient light on the environment. So let's get started