Since a number of residential houses in Japan have built before 1980, they have very poor thermal insulation. With poor thermal insulation specification, the indoor thermal environment in winter could be so uncomfortable. The low temperature in houses could cause occupants' common cold, higher blood pressure, heat shock, and many other diseases.<br> Chapter 1 comprised previous studies, including ones about CASBEE Housing Health Checklist, and introduced the purpose of this research.<br> CASBEE Housing Health Checklist by Japan Sustainable Building Consortium (JSBC) is a type of software used to assess the health of residences. Answering 50 questions allows residents to identify the aspects of their home that affect their health. The score on the warmth is the sum of points for 7 questions about warmth in the checklist. The perfect score for each question is 3 points, therefore the perfect score for 7 questions is 21 points. Questions about warmth are intended to evaluate the thermal environment of both living rooms and non-living rooms. The first question is about the coldness of living room, the 2nd is about the coldness of bedroom, the 3rd is about the dryness of the bedroom, the 4th and the 5th are about the coldness of sanitary spaces, the 6th is about the coldness of toilet, and the last question is about the coldness of Corridor/Stairs/Closet. Examples of questions are as follows: “Do you feel cold during heating the living room?”, “Do you feel cold in the toilet in winter?”<br> The purpose of this research is proposing a method to calculate the score on the warmth, and making it possible to evaluate health performance of detached house by using room temperatures of simulation results. As using this method, it could be possible to indicate the necessity of thermal insulation of houses or help the occupants to consider an improvement of thermal insulation performance.<br> The calculation method to calculate the score on the warmth in a house is proposed in Chapter 2. Score on the warmth in CASBEE Housing Health Checklist is calculated from the temperatures that are simulated in the previous case study using a heat load simulation. The method to calculate the scores from temperatures is based on other studies about thermal sensation, health, dwelling performance and so on. For example, the score to the question of “Do you feel cold in the toilet in winter?” is calculated from operative temperature (OT), floor surface temperature of the toilet, and the OT difference between the bedroom and the toilet at late-night. Regarding converting OT into scores, 8°C corresponds to 0 points, and 15°C corresponds to full points. This allocation is decided based on the study that indicates the average toilet temperature that occupants felt cold was approximately 8°C, and the average temperature that does not feel cold was approximately 15°C.<br> Using the score on the warmth, it is possible to predict the crisis rate of catching a cold in winter. The predicted crisis rates are indicated in Chapter 3. The temperatures calculated in the case study simulation of houses with various thermal insulation levels are used to predict the crisis rates. For example, if a house with no insulation is replaced with a house which insulation performance meets the Japanese energy saving standard (so-called “H25 Standard”), the score raises approximately 6 points, and the rate of catching a cold in winter decreases approximately 15 %.