Spray foam insulation replaces the pink fiberglass insulation that has filled most standard wall cavities over the past half-century. (Katherine Frey/The Washington Post)

We are caught up in a tornado of buzzwords swarming mainstream media, design and essentially every facet of our  lives. Green, sustainable and energy-efficient are labels slapped onto all scales of merchandise (from tissues to appliances to building materials) to accommodate a well-intentioned trend that has gained significant traction over the past decade.

Environmentally conscious strategies have persisted (sans label) for centuries — even millennia. Ancient cities employed passive solar and air ventilation techniques; construction materials were selected for their heat retention or air-circulation qualities. The profession of architecture is among the oldest in civilization, and long before the luxuries of air conditioning and heating, we were charged with the responsibility of designing safe and comfortable shelters.

The No. 1 factor that will dictate the energy efficiency — and therefore sustainability — of your home is the building envelope. We assume our homes are built with solid structure, without gaping holes to allow insects and vermin to infiltrate. But what about that invisible, insidious guest: unconditioned air?

Any contained space needs fresh airflow and circulation, but that air is controlled through a building’s mechanical systems. It is not supposed to (and houses are not designed to have it) sneak in through cracks and seams in the building envelope. Whenever you have the heater or air conditioner on, your HVAC system is burdened with the extra load of conditioning the air that is leaking, uncontrolled, into your house, which results in your system working harder, consuming more energy and wasting electricity. The way pennies and loose change quickly add up to dollars, many little (and not so little) imperfections in your building’s envelope can easily add up to leaving the front door open while you blast the A/C during the dog days of summer.

Among the most popular and effective building envelopes for new construction are spray foam insulation and construction with structural insulated panels (SIP).

Spray foam insulation replaces the pink fiberglass insulation that has filled most standard wall cavities over the past half-century. Instead of this pink, itchy fluff occupying the space between wall studs, a polymer and foaming agent are combined to expand nearly to 100 times their original volume, filling every crack and crevice. Traditional fiberglass insulation allows for about 30 percent of your heat or air conditioning to leak out of the house; spray foam insulation allows essentially no air to escape (or infiltrate). Spray foam insulation, compared with fiberglass insulation, has a superior resistance to heat loss, more than triple the life span and won’t accumulate dust or pollen.

An even more effective new building option is SIP construction. These panels are simple in composition: Rigid foam is sandwiched between two layers of sheathing (oriented strand board, a.k.a. OSB). That’s it! The house plans are sent to the SIP manufacturer, and the walls are delivered straight to the job site, ready for assembly. Each wall, corner and roof piece fits together like a glove and is caulked at intersecting points to give a final seal to the seams. All utility lines can be pre-cut out by the manufacturer, making the assembly and the utility rough-ins as easy as anything in construction could be. Not only does this building option offer a superior envelope, but significant time and labor are saved in the construction of this ultra-energy-efficient option.

With each of these new construction options, there is minimal off-gassing of materials. And — in the case of SIP — there essentially is zero construction waste, leaving you with nothing but a tight building envelope, secure from infiltrating air (and also water).

If you are renovating an existing home without the opportunity to reconstruct or reinsulate all of the walls, there are other ways to improve your energy efficiency.

As we consider the building envelope of a home, what are the obvious culprits of escaped conditioned (or intrusive unconditioned) air? Doors and windows — these are straight punctures into your building’s envelope.

The biggest issue I see with homeowners’ exterior doors is a poor fit. If light can get through your door and its frame, so can hot and cold air. Most of the time, this is a result of the house settling and can be mitigated with DIY weather stripping that can be picked up at the hardware store.

Windows can be more complicated. Quick-fix solutions can be found at the hardware store to keep cold air out, such as window-insulating kits with adhesive and a thick plastic shrink-wrap that you use a hair-dryer to fashion in place. Though this is a helpful short-term solution, you need to apply it (then take it down) seasonally, and it is only superficially helpful. Similarly, purchasing insulated drapes/window treatments can help but requires the curtains be drawn (which would block any natural light and view of the outdoors).

For addressing the opposite problem — windows that beam enough sunlight in to fry an egg on a cold plate — insulating drapes can help resolve the symptom but not the problem. If you can prevent the sun from beaming onto the glass from the outside, you do not have to worry about mitigating its heat on the inside. This is most successfully achieved by adding overhangs onto the exterior above your windows.

The size of these overhangs is calculated based on your geographic coordinates, to ensure they will allow sunbeams (and therefore heat) to reach the glass during the cold months but be blocked during the hot months. Unlike older window awnings or even functioning shutters, the overhangs of today’s architecture are intentionally designed not to obstruct your view of the outdoors.

These solutions are better than nothing. However, the hands-down most effective solution to solve energy-poor windows (especially important in conjunction with an effective overhang design) is to replace the windows themselves. Double-pane windows offer significantly better insulation than single-pane windows because they have an insulating air gap between the two pieces of glass. But the details do not stop there: When the air between the windowpanes is filled with argon gas, it is much better insulation than our normal oxygen- and nitrogen-filled air. In addition, the glass itself is important: low-e means that the heat in the summer or cold in the winter will not radiate through the glass as much as it would with regular glass.

It is best to consult your architect on window details, as the direction your windows face will influence factors such as the conductance and solar heat gain coefficient (SHGC), which should be different for south-facing windows because of their significantly higher sun exposure throughout the day.

There are a number of modern internal technologies that can contribute to a more energy-efficient and sustainable home. Low-flow toilets from the big-name brands — Kohler, for instance, which has a patent on its new, innovative flush systems — outperform the standard toilets with which we grew up, consuming far less water yet flushing much more effectively.

Unlike “green” or even “energy-efficient,” which are unregulated terms and can be highly subjective, Energy Star appliances are certified to consume less energy based on baseline standards set by the Environmental Protection Agency. Purchasing appliances and mechanical systems with this seal of approval will help contribute to better energy savings (to varying degrees, depending on the kind of unit) than their alternatives.

With compact fluorescents as their steppingstone, LED lights are now leading the way as the most energy-efficient lighting option. Compared with the beloved incandescent, LEDs consume just trace amounts of energy (which translates to electricity) to illuminate your space. LED lighting has made the worry of accidentally leaving the house lights on and driving up your electricity bill obsolete.

Unlike their CFL predecessors, LEDs come in practically limitless colors/temperatures. This includes 2700K, which is typically seen as a slightly brighter equivalent to the warm glow of the incandescent, and 3000K, which is a slightly whiter “warm white” than the 2700K and a popular selection among residential designers for most living spaces.

Offered in a wide variety of “bulb” sizes, LEDs can replace many, if not all, of the lightbulbs around your home — and research shows you are likely to move out of your house before you will need to replace your LED lightbulbs.

One of my favorite energy-saving innovations over the past few years has been the ease of customized climate control. Most people are not diligent enough to turn the heat (or air conditioning) down or off when they leave for an eight-hour work day — and even if they are, turning all systems back on when they get home does not immediately condition the space to the desired temperature. For years, there has been a small market for digital, programmable thermostats, but to make any out-of-schedule adjustments (during the holidays, for instance, or a staycation) involved a complicated process that was akin to changing the clock on the VCR.

You can now control your entire HVAC system with an app on your phone. The Nest is the most widely known smart thermostat that can (though it does not need to) connect to your smartphone. You can program this system manually with the user-friendly digital thermostat or set/change/override its schedule with a click on your phone. You can also let it do all the work to learn your weekly schedule, and it will self-adjust your energy systems based on your routine. This way, the heat can drop to 65 degrees when the house is empty but will be warmed up to 72 by the time you walk in the door.

Whether you are building a new house or reevaluating your existing home, there are many options available to work toward improved energy efficiency and lower utility bills.

Stephanie Brick is the owner of Stephanie Brick Design in Baltimore.