A Couple of Easy Strategies for Energy-Efficient Home Design

If you’re not yet giving much thought to how much energy your new  house is going to use, and how much it’s going to waste, then it’s time  you started.

It should be one of your top priorities – if  for no other reason than your own pocketbook.

Energy  used for heating and cooling homes is going to continue to get more  expensive and as we've seen recently, world politics can quickly and  dramatically affect your access to cheap energy.

Saving  energy isn't just about saving money, however - it's also an important  part of good design.

A Little History

This isn't the first energy  crunch we've had. In the 1970’s – when I was a college student studying  Environmental Design – world events conspired to create an American  energy crisis. It was an interesting time to study Architecture, because the buildings we designed were required to respond to the environment –  to use natural energy sources as much as possible.

The  homes we created used climate-reponsive design to give them form  – we designed solar homes, earth-sheltered homes, thermal-mass homes,  and other types in a wide variety of shapes and sizes. They collected  heat from the sun and the ground and held it inside as long as possible.  They blocked excessive solar radiation with deep overhangs and shading  devices, and they were very carefully oriented to the angle of the sun  and prevailing winds.

Sure some of them looked a little weird  (some were downright ugly) but the homes we designed stayed warm in the winter and cool in the summer and used almost no energy at all.

But  then in the 1980s energy got cheap again, and everybody forgot about  low-energy homes.

Where We Are Now

Fast-forward  to the twenty-first century and suddenly energy is on the front page  again. And again homes are responding to pressure to reduce energy  usage, but in a curiously different way – through envelope and  mechanical technologies.

Envelope Technology

The  “envelope” of your home is its wrapper – the roof, walls, windows, and  foundation. It’s what keeps the outside out. There was a time when heat  flowed rather freely through the envelope; windows were single-pane  thickness and walls and roofs had little or no insulation.

Today,  wall and roof assemblies can be very high-tech. New types of  insulation, sheathing, and siding slow heat flow to a crawl.  Infiltration barriers (Tyvek, Typar for example) stop excessive water  vapor migration and seal the outside more tightly than ever. Houses can  be sealed so tightly in fact, the trapped moisture can accelerate mold  growth (that’s a subject for another time).

Windows  and doors have also gone light-years beyond the old wood-framed  putty-glazed sashes of the early twentieth century. Windows today are  offered with multiple panes of glass sealed together to create an  insulating layer within; often that “airspace” is filled with inert  Argon gas – which has a higher resistance to heat transmission than air. 

The framing of the windows is far better sealed, and  the installation methods are much improved. Even plain old glass isn't  what it used to be – now it’s coated with a microscopic layer that  allows sunlight in, but blocks Ultraviolet rays and helps keep heat from  escaping.

Other high-tech wall technologies include  ICFs (Insulated Concrete Forms), and SIPs (Structural Insulated Panels). 

Mechanical Technology

The  other area of big change is mechanical technology, including  groundwater-source heating and cooling systems, active solar collection  panels, and on-demand water heaters.

Furnaces, heat  pumps, heat exchanges, boilers, and air conditioners are more efficient  that ever and work hard to squeeze every BTU of energy out of the fuels  they use. And sophisticated computer control systems manage the  distribution of heat throughout the house.

Design  For Energy Efficiency

Envelope technology and  mechanical technology are two ways to make any house design more energy  efficient. High-technology energy management systems can be added to any  house design, and most can be easily modified to include the latest in  envelope technology.

But envelope and mechanical  technologies aren't the only way to create a more energy-efficient home.  “Back in the day” we did it with old-fashioned good design – by paying  attention to solar orientation, window quantity and location, and house  shape and size.

Blown Away

In the temperate and cold climates of the United States, for example, winter winds typically blow from the west and northwest.  And they'll draw heat away from any surface they strike.

The harder the wind blows, the more heat it carries away.

That's why old farmhouse are almost always placed to the southeast side of a grove of trees, or behind a small hill - to block or slow the winter wind.

You can do that with your home too - an existing hedgerow or treeline will help. Or plant a group of evergreen trees on the west/northwest side of the house.

Another easy strategy is to put spaces that don't require heating on the west and northwest sides - your garage, or maybe a storage room.  That's just as effective as a hill or treeline.

Here Comes The Sun

Sunshine is one of those things (like a neighbor) that's great to have around when you want it, but annoying when you don't.

The warm feeling of bright sunshine, heating a tile floor in the middle of winter, is welcomed.  The trick is letting the sun in and keeping it there.

Properly-placed windows on the south side of a home (in northern latitudes) can allow a surprising amount of winter sunshine and heat into your home.  Get that sun to shine on a dark surface - preferably masonry - and you've got a thermal mass or heat sink.  A thermal mass absorbs heat during the day, and radiates it back into the house at night.

It's also a passive solar design strategy - no moving parts, no energy used.

Keep Your Cool

But eventually summer comes, and that same sunshine you welcomed in January is baking you in July.

Fortunately, our little blue planet has it's axis at an angle to the sun, which means the sun is much higher in the sky in the summer.

You can use that to your advantage by designing a short overhang above your south-facing windows - your solar shade should be long enough to block the midday sun, but short enough to allow the winter sun in.

Easy, cheap, passive, and it works.

Before you start your new home or remodeling design, give careful  thought to how the design - not just the envelope and mechanical systems - will impact its energy use.

Need expert Residential Architectural advice for your new home or remodeling project? Contact Richard Taylor, AIA at RTA Studio Architects to arrange a meeting or an online consultation.