Donna's loft apartment is in a great location and has many amenities, however I was really surprised at how hot the apartment got during the day -- and how hot it stayed at night. There isn't AC, which I learned upon arrival. I visited in late October, and the apartment felt about 80° F. I don't want to know what it's like in the summer months.
The apartment's one ceiling fan doesn't particularly help, and it definitely doesn't add any airflow to the upstairs bedroom. Donna suggested opening the windows and leaving the curtains drawn during the day, and I did not notice a difference on the second night of my stay, besides lots more noise coming in from outside. So, unfortunately I was a little disappointed in my choice during this trip to SF.
Donna doesn't list AC under the amenities, so it's not as though the listing is inaccurate. However, it's not apparent there isn't AC or a window unit until you look pretty far down in the listing's information. I realize it's my fault for not doing all my research before booking, so there's that. However from the reviews I read, no one else mentioned a temperature issue.
That said, I think supplying a simple oscillating fan would go a long way. Not being comfortable -- particularly at night due to being hot -- hurts the value of this listing, especially since you're already paying a premium for Hayes Valley in SF.