The environmental survey was intended to study the internal conditions inside the Nijo Castle at Kyoto, a typical Japanese historical wooden building, to see how well its architecture, with long eaves, paper sliding doors and wide corridors, had withstood external climatic conditions. Plans show where the hair hygrometers and thermal sensors were positioned. Ultraviolet photometers were used to measure intensity, and samples of litharge (stable to rh below 40% but changing to dark green with increasing rh and light exposure) and rhodamine b (fading in light) were used to check light exposure. The conclusions were that the construction did attenuate the outdoor conditions and that stray light entering was sufficient to bring about changes in the samples used. Charts, histograms, diagrams, plans.