Urban Heat Island

[City_boy12]

I've heard that a unit in a highrise uses needs less energy to heat and cool it than a suburban house does, but because of the urban heat island effect, could highrise units actually use the same or even more energy than a single family house???

[Nowhereman1280]

^^^ It has nothing to do with the heat island effect. The biggest reason highrises are more efficient is that they have a smaller surface area than the same amount of sqft in single houses. Think about it, if you have a 1500sqft house, you have all four walls plus the roof facing the outdoors, losing heat (or gaining it in the summer). If you have a 1500 sqft condo, you only one maybe two walls facing the elements, therefore you only have to worry about the heat escaping from those walls. Thus, you have a massive saving of energy loss.

Another reason its more efficient is that when you have a High Volume Air Conditioning (HVAC) unit, it tends to be more efficient than a bunch of single air conditioners and therefore saves everyone energy.

For example, I live in a 1000 sqft condo on the 49th floor and used the air conditioning maybe two times this summer. Between AC leaching into my condo from my neighbors, the natural cooling provided by the thermal mass of the concrete in my building (its Reenforced Concrete) and the exceptional air circulation you get by being this high, it really never gets cold or hot in my apartment but hovers in the "just right" zone.