Conflict of interest
TI has received research grants from Tokyo Gas Co., Ltd., Osaka Gas Co., Ltd., Panasonic Homes Co. Ltd., Fuyo Home Co. Ltd., Asahi Kasei Homes Corp., LIXIL Corp., Azbil Corp., Kajima Corp., Shimizu Corp., Nice Corp., Japan Gas Association and Japan Sustainable Building Consortium. KK has received a research grant from Omron Healthcare Co., Ltd. YF has reported grants and personal fees from Saibugas Co., Ltd. MS has received non-restrictive research funds from Taiyo Nippon Sanso Corp. TH has received honorarium from LIXIL Corp. The above grants/funds/honoraria were all received outside the submitted work.