The Power of McMansions

McMansions aren't just ugly...

The recent increase in the building of "McMansions" - extra-large homes that replace modest mid-last-century ranch homes and seem to swallow up an entire suburban lot - has long been controversial from an aesthetic point of view.

Now the overall environmental impact of large homes has come into question. At the heart of the debate is whether monster homes - dwellings larger than today's average of 3,500 square feet - use more energy than smaller ones.

Comparing the relative green qualities of a small home with those of a big one is complicated. How do you define the size of the homes? Are larger homes, because they tend to be newer, more efficient due to the use of state-of-the-art building materials?

That said, even Pacific Gas and Electric Co. says that if Home A is one size and Home B is twice that size, Home B will probably use double the amount of energy.

The utility bases its conclusion on what's known as a Residential Appliance Saturation Study. It shows that multi-family buildings - apartments, condos and other dwellings that have shared walls - use less energy than single-family dwellings.

This isn't the same as comparing small homes against large single-family homes, but it does show that smaller dwellings tend to use less energy.

The study has a bright side for energy-conscious owners of newer homes, defined as those built after 1996. It shows that a new 2,039-square-foot home compared with an old 1,434-square-foot home - a 42 percent difference in size - uses only about 20 percent more electricity and 2 percent more gas. This is because of the use of energy-efficient construction and appliances.
It's also difficult to discount the energy hog factor - what difference does size make as far as energy consumption is concerned if the inhabitants are blasting five plasma TVs, three computers and a space heater in every room all day long?

But even when you eliminate that factor, some fixed costs associated with maintaining a dwelling are hard to get around.

Not surprisingly, chief among these are heating and cooling.

The ability to create zones within a house with separate thermostats for heating and cooling specific rooms may seem to solve this problem, but larger homes with unheated or cooled rooms can still waste energy.

This is because the rooms can easily become an "energy sink."

"Let's say you've got a whole guest suite with the guest bedroom and the bathroom and it's adding 3,000 square feet to your house, even if we do cut off the heat and the air conditioning to it ... there's still this big volume of room that is being placed in the sun," said green architect Eric Corey Freed, author of "Green Building and Remodeling for Dummies" and a principal with Organicarchitect in San Francisco.

"If it gets hot, it'll heat up the rest of the house and if it's one of those places that's always cold, it'll cool down the rest of the house. It can really work against us."

Do monster homes use more energy? [San Francisco Chronicle]