This building is Taipei Public Library Beitou Branch. And this is a Green Library. Why is this the case? 

The sloping roof preserves humidity and moisture build-up and drains water to rainwater recycling troughs. Then, the recycled water is used to water plants and flush toilets in the facility. This arrangement result in reducing water and resource wastage. Another thing, the rooftop has photovoltaic cells which are in place to capture solar energy and in turn, generating 16 kilowatts of electricity. Awesome, right?

The hot spring water is flowing just next to the library.

If you want to have a taste of how the hot spring feels like for free, you can do what the locals do. Just find a place to sit and soak your feet inside the stream. The feeling must be very comfortable in winter days. 

Oh one thing to note, do not go for hot spring activity a day after typhoon. Simply because the water will look like...chocolate milk. Took this picture exactly one day after Typhoon Soulik passed. Well, some people still went for it though. Haha.

At the end of the road, you will see a lot of people taking a cross following the direction to Beitou Thermal Valley. 

The smell of the rotten eggs (i.e. sulfur) is on the air...

And finally, we have reached the Beitou Thermal Valley Sulfur Spring. If you put a raw egg inside, it will boil. And you can eat it. XD

It can get pretty hot and steamy here. If you can, do visit the spring in the colder days. =)