Explain that the home is not ventilated, the light is insufficient, or it is humid. Another possibility is that furniture and other items are old and dirty. This will affect the mood. So what we have to do is to pay attention to ventilation, light transmission and cleanliness. If the light is insufficient, use high-power light bulbs and fluorescent lamps (the ones that are particularly bright during the day). Windows should be clean and ventilated more.
Basically, it will be fine after adjustment.