1種換気と3種換気はどちらが良い？

Today's topic is ventilation systems. I'd like to share my current opinion on whether Type 1 or Type 3 ventilation is better. First, do you know the difference between Type 1 and Type 3 ventilation? To briefly explain, 24-hour ventilation is mandatory in Japanese homes. The reason for this is to prevent sick building syndrome. It's mandated that ventilation systems be installed to keep the air fresh at all times. There are three main approaches to ventilation. The first approach is Type 1. Ventilation isn't achieved by ventilation alone. There's supply air and exhaust air, and ventilation is achieved when these two circulate. Supply air is drawn in from outside and brought into the room. Exhaust air, on the other hand, is expelled from inside the house using a fan. Both supply and exhaust are performed mechanically, using a fan. Furthermore, heat exchange is performed, bringing the outside air closer to the room temperature before intake and exhaust. This is Type 1 ventilation. Type 3 ventilation is simpler. Regarding air intake, it's simply a louver (vent). Exhaust is forcibly expelled by a fan. Range hoods also have a mechanism for forcibly expelling exhaust. Incidentally, there are Type 1 and Type 3 ventilation systems, and also Type 2 ventilation. In this system, intake is mechanical, and exhaust is natural. Type 2 ventilation is used in sterile rooms in hospitals, and is rarely used in homes. Returning to homes, both Type 1 and Type 3 ventilation have their own advantages and disadvantages. We'll discuss how to choose between them. There are said to be three perspectives for making a decision. The first is comfort. Which is more comfortable to live in: a house with Type 1 ventilation or a house with Type 3 ventilation? The second is utility costs. Since ventilation is involved, utility costs will increase. In addition, you'll be using heating and cooling appliances, so you need to consider not just ventilation costs, but also the combined costs of ventilation and heating/cooling. The third is initial cost and running costs. Initial costs are the expenses incurred when installing equipment, while running costs are the expenses incurred after installation, i.e., maintenance costs. I have a respected engineer named Kyosuke Mori. He is an expert in thermal and ventilation systems and also has a YouTube channel, which I often learn from. Mr. Mori has a very clear example from his simulations. Let's say it's winter, the outside temperature is 0°C and the humidity is 70%. The simulation compares a house with a room temperature of 20°C and humidity of 40% to a house with a Type 1 ventilation system and a house with a Type 3 ventilation system, and shows what happens after one hour. Type 1 ventilation, of course, involves heat exchange. After one hour, the room temperature was 18°C ​​and the humidity was 38%. The room temperature only changed by about 2°C, which is quite efficient. With Type 3 ventilation, after one hour, the room temperature was 10°C and the humidity was 55%. The room temperature dropped by 10°C! Therefore, in terms of comfort in winter, Type 1 ventilation, which exchanges heat, is superior. What about summer? Let's say the outside temperature is 35°C and the humidity is 55%. Let's also assume the indoor temperature is 26°C and the humidity is around 50% with the air conditioning running. Looking at the changes after one hour, as before, in a house with a Type 1 heat exchange system, the room temperature went from 26°C to 26.9°C and the humidity went from 50% to 60%. In a house with a Type 3 ventilation system, the temperature went from 26°C to 30.5°C and the humidity went from 50% to 55%. While the changes aren't as dramatic as in winter, the room temperature still fluctuates considerably in summer. Therefore, it's understandable why people who recommend Type 1 ventilation say the comfort level is significantly different. On the other hand, let's consider the energy costs. This calculation takes into account that the most common ventilation systems in Honshu (6 regions) are Type 1, and that the program for estimating energy-saving effects is the default. With Type 1 ventilation, the annual heating cost is ¥33,689, the cooling cost is ¥16,698, and the ventilation cost is ¥27,675. This simulation shows a total utility cost of ¥78,062. (This is roughly the actual cost.) On the other hand, with Type 3 ventilation, heating costs clearly increase, but cooling costs don't change much. The simulation results show heating costs of ¥37,368 and cooling costs of ¥16,698. It's strange, isn't it? Everyone experiences the intense summer heat, so you might think that ventilation would significantly reduce the cool air, but air conditioners are surprisingly efficient and can maintain a cool environment without spending too much money. Therefore, we would like you to keep using your air conditioner and not turn it off. So, the cost of ventilation with a Type 3 ventilation system ...