The housing industry uses a number of gauges to determine the state of its health.

One of the more interesting is the American Institute of Architects' monthly billing index, a survey of firm principals and partners designed to track business conditions as they change.

The index reflects the nine- to 12-month lead time between architecture billings and construction spending.

As with most housing-industry indicators, it has shown steady improvement over the last 12 months, after several negative years between 2007 and 2012.

The institute also tracks trends in construction and renovation, which I consider to be much more informative about what consumers want than most of the dot-com surveys that fill my in-basket each day.

What people want and what they shell out big bucks for are usually very different things.

I've been writing about real estate in this space for almost 26 years, and I've tracked hundreds of trends - some enduring, such as over-55 housing and energy efficiency; some one-shot deals, such as urinals in garages (I'm not kidding).

One thing I noticed in this index is that much of what is considered a trend at the moment actually isn't new.

For example, the demand for special-function rooms was on hiatus during the financial downturn, as homeowners couldn't see adding to remodeling or construction costs with outdoor living rooms, mud rooms, or home offices.

All three are back in demand, says Kermit Baker, chief economist for the architects institute.

The number of self-employed workers appears to be growing, he says. Plus, as companies continue to shed full-time workers, the employees who remain are often unable to handle the resulting load within a 40-hour week at the workplace.

Yet home offices apparently aren't the formal spaces designers insisted that we wanted, with large mahogany desks, wall-to-wall bookshelves, and separate entrances for clients.

Instead, the technological revolution, WiFi, Kindles, smartphones, and cloud storage have decluttered these spaces into stripped-down functionality, the experts say.

Demand for home automation is driving many of these changes.

Architects say that wireless telecommunications and data systems, long-range electrical controls/smart-home systems, and automated lighting controls are in demand.

With consumers generally more comfortable with emerging technologies, and the prices of many of these falling as production volumes increase, home automation should increase.

Also affecting the index is "evolving household composition."

Employment is growing, architects say, and with two-paycheck families the rule, the demand for in-law/au pair suites is increasing.

"As many households become caretakers for aging relatives, separate living suites have become popular alternatives," Baker says.

That leads to a growing demand for accessibility in both new construction and upgraded older homes, the architects say.

One pre-downturn trend with few takers these days is the media room/home theater.

I remember when "SurroundSound" and big screens were all the rage, and higher-end builders' model homes had carpeted basement rooms with more comfortable seats than the local multiplex.

Now, everyone sits on the couch with Bose headphones plugged into iPads with an Xfinity app.

The only sound you hear is, "Pass the popcorn."

215-854-2472 @alheavens