How to improve daylight in residential Thai houses, based on Swedish knowledge? As everyone knows in Thailand there is a huge amount of sunlight during the whole year. Although, when architects design a house, normally, daylight is blocked and is not used considerably, especially if compared with Sweden, a country which has limited sunlight. Therefore, if Swedish knowledge could be adapted to be used in Thai houses, maybe it would be a progressive improvement in taking advantage from sunlight in residential house. From the main idea, research and comparison between the two countries and example of their architecture were used as starting point to find the principles which can be adapted to suit Thai environment. Afterwards, adapting those principles idea and testing to find out what is the suitable principle of Swedish knowledge that can be used in comparable Thai situation at least for four extreme periods during the year. Eventually, from the test, suggestions for adapting daylight to use in Thailand were developed, and point to some new ideas for future improvements.