Sustainable Design Center » Strategies & Techniques

PAE’s Six Steps to Net Zero Energy

One of the assets PAE brings to projects is our holistic approach to minimizing a building’s overall energy use.

OUR APPROACH FEATURES SIX KEY STEPS:

Set Aggressive Goals

This may seem obvious but in fact, failure to establish clear goals — especially aggressive ones — is one of the surest ways to limit your achievements in sustainable design. Some projects aim to achieve Net Zero Energy, some to be 50 percent more efficient than code, and some even strive to be restorative to the surrounding environment.

Analyze the Climate

We carefully analyze the local climate, looking beyond the hottest summer or coldest winter days to consider weather data for all 8,760 hours in a year. We look for diurnal temperature swings and temperature “bins” to determine how many hours per year the temperate falls within given ranges, solar radiation, rainfall data, wind velocities, relative humidity, and other factors. This careful analysis reveals opportunities for passive heating and cooling, potential options for renewable energy generation, and envelope designs that result in low “balance point temperatures” (the temperature at which the heating system will need to turn on), among others. For a look at the types of data we collect and assess, see climate considerations.

Reduce Energy Use

In order to save energy, the design team needs to know where in the building energy is most likely to be used. In a typical Northwest office building, for example, about 40% of the energy used is for heating, 10% for cooling, 25% for lighting, and approximately 15% for office equipment and other plug loads. The remainder is used in water heating, fans, and pumps. To assess energy performance for a specific building or design, we develop energy models and also compare projects to similar projects we’ve done before. We work closely with the architect to optimize the building envelope, making recommendations for glazing percentages, wall and roof insulation, glazing U-values and shading coefficients, and infiltration rates.

Choose Efficient Systems

By carefully completing the first two steps, we can typically reduce the size of the MEP systems or in some cases eliminate costly systems. During the schematic design phase we outline options for both electric and hydronic heating as well as carbon neutrality. We assess impacts on the architecture and on estimated first costs, maintenance costs, operating costs, simple paybacks and life cycle costs.

Opt for Renewables

During the schematic design phase we evaluate the options for on site renewable energy sources including daylighting, passive heating, passive cooling, solar thermal, solar electric (photovoltaics), biomass and wind power. We also assist owners in working with third-party suppliers who may be able to finance such systems off the project’s balance sheet.

Verify Performance

The only way to determine if a building or system has achieved high levels of efficiency is to measure its actual performance. Such post-occupancy data is required for any building seeking Living Building status, will soon be required for all LEED buildings, and may be required for some types of government funding. Owners may benefit even more from knowing where their building uses energy — how much goes to lighting, to heating and cooling, to plug loads, and to other energy applications. PAE provides such information via detailed monitoring and verification services. Through analysis and retro-commissioning we help owners hone their system settings and facilities management practices over time. There’s also a longer-term, community-wide benefit to performance verification. It enables design firms and owners to see the actual difference between performance and energy models, examine the reasons for differences, and apply that knowledge to the next design. PAE maintains a database of this information, using it to inform the next design to achieve greater accuracy in energy models and greater levels of energy efficiency.