Energy and Atmosphere

With increasing prices and changing supply, it is crucial to use energy wisely.   Follow these 5 steps to plan your energy strategy.

Determine Benchmark and Set Goals

Begin with determining how much energy your home or building consumes, or is projected to consume.  This will be your benchmark.  Gather utility bills to evaluate kilowatt (kWh) used in an existing project or a similar building type in the region.  In the absence of such data, predictions are based on computer simulation models.  A standard new house in this area consumes 14,700 kWh of energy annually.  The goal is to reduce this number by two-thirds to 5000 kWh.

Plan Passive Features/Strategies

Understanding the macro and micro climate and employing climate-appropriate passive design strategies are the first steps in sustainable design.  Houston’s climate is subtropical and humid with 3058 Cooling Degree Days and 1599 Heating Degree Days.  That means we need air conditioning over 60% of the year.  Passive strategies such as shading and natural ventilation can bring comfort to outdoor and indoor spaces and reduce the demand on active mechanical systems.

Shielding buildings from the heat of the sun is crucial on the East, West and South facing walls.  Take a look at which areas of your building receives sun during the afternoon and incorporate shading strategies such as planting trees, growing vines on a trellis or attaching canopies or overhangs.  Applying a window film with an SHGC (Solar Heat Gain Coefficient) less than 0.30 helps block the sun’s heat.

When designing a new building place infrequently used spaces, such as closets, laundry and mechanical rooms in the East and West portions of the building.  This keeps regularly occupied spaces in North and South zones, where it is easier to control heat gain from the sun.

In general, dark colors absorb heat; light colors reflect heat.  Selecting light colors for roofing and exterior painting helps reflect heat from the sun.

On days when the humidity is low and the temperature is mild turn off the A/C and open windows and doors to allow natural ventilation.  Window and door screens allow air to flow through but keep the bugs out.

Use Efficient Components and Systems

Houston energy code sets the minimum standard that new building and renovations must comply with.  The code is based on ASHRAE standards and the International Energy Conservation Code (IECC), adjusted to account for Houston’s climate.  Buildings and homes, depending on their size and shape, could be envelope dominated (example: homes), internal load dominated (example: office buildings) and outdoor air dominated (example: laboratories) strategies should address these high impact areas according to building type.

Energy efficiency

Cooling Load Components in a Typical House

In homes, a highly efficient envelope could help reduce energy consumption considerably, while in offices efficient lighting and mechanical systems would be more effective as individual strategies.  Efficient fume hoods and energy recovery systems provide more value in laboratory buildings as compared to other strategies.  Controlled daylight and occupancy sensors further reduce lighting and cooling loads and are effective across multiple building types.

Use Renewable Energy Features

Renewable energy comes from sources as varied as the sun, wind, hydro (water), the earth, and ocean waves.  Its use reduces consumption of fossil fuels and mitigates greenhouse gas emissions that cause climate change.

For solar collector surfaces with horizontal and latitude tilts, Houston receives an average annual daily solar radiation of up to 5 kWh/m²/day that makes it ideal for electricity generation through solar photovoltaics (PVs) and solar hot water generation.  Houston’s average annual wind speed is a low 9 mph, and is not consistent enough to generate significant amounts of power like West Texas.  But future technologies may bring residential wind power mainstream.

Renewable energy generation can be both supply side (at power plants) and demand side (point of use/buildings).  On the supple side, wind farms in West Texas send electricity through the state-wide utility grid.  Purchasing Renewable Energy Certificates (RECs) compensates these suppliers for extra cost incurred in renewable energy generation and encourages investment in improving technologies.  Also known as Green Tags or Tradable Renewable Certificates, RECs allow consumers to continue to purchase power from their contracted energy provider, while making an additional payment to support renewable energy generation.

On the demand side, solar panels may be a viable option for your home or building.  Solar Cost Calculator at is a tool that helps determine sizing, cost and payback information for photovoltaic, systems up to a certain size.

Maintain a Well-Functioning System

Properly maintaining your building and associated systems will ensure optimal energy-efficiency.  When installing new equipment, find out the maintenance suggested by the manufacturers.  For example, photovoltaic panels may need to be cleaned periodically and checked for damage.  Inspecting around windows and doors for leaks, and adding caulk or other sealant where necessary, combats air transfer through the envelope.