Ten engineering strategies that really work in practice.

When designing with sustainability as a goal, there are many options available to architects and engineers. The real question becomes, what are the most practical alternatives to enhance the energy efficiency of your design?

With 25 years of experience in developing sustainable design strategies here are some of Ambrosino, DePinto & Schmieder's engineering strategies that really work in practice.

Day lighting/dimming systems/ lighting upgrades

Utilizing daylight in lieu of artificial light can save significant amounts of energy. In addition, natural light is more pleasing and less straining the eyes, which may lead to higher productivity. Combining day lighting with electronic sensor controls can minimize electrical energy use, and by dimming or turning lights off when there is sufficient natural light, wasted energy is minimized. To do this, Photocells are used in conjunction with occupancy sensors, which shut lights off when rooms are empty, and electronic sensor control provides the maximum energy efficiency for lights.

Electric generation

Electric generating technologies can also save energy. Photovoltaic panels use pollution-free technology to convert the sun's energy into electricity. Wind and sea turbines can also be used to harvest the power of air and water currents. Currently, photovoltaic and turbines are feasible only on larger scale projects, however continuous innovation means that these systems can soon be applied profitably to smaller and smaller jobs. Photovoltaic panels can now be built into transparent windows, further easing their design integration.

High efficiency fixtures

Facilities can save money while conserving water by installing high efficiency fixtures. These include waterless urinals, low flow toilets and showers, and electronic flush valves and faucets. Waterless urinals employ a cartridge with immiscible fluid to remove the requirement for flushing water. This saves installation cost and roughing materials. Low flow fixtures use less water while delivering comparable performance to standard fixtures. Some toilets have dual flush capabilities for different wastes, while others are designed to flush with 1.2 gallons or less of water, compared to the standard 1.6 gallons. Showers are designed to use less than 2.5 gallons per minute, and some even flow less than 1.5 gpm. Finally, electronic faucets can be timed to run for 10 seconds or less, and electronic flush valves keep repeat flushing to a minimum. All of these technologies allow for water savings over standard fixtures.

Gray water collection

Facilities can also save water by using a gray water recycling system. By filtering the wastewater from non-fecal fixtures (sinks, lavatories, showers and washing machines) and reusing this water for flushing or other non-potable systems, the demands on both the incoming water service and the outgoing sewer service are lessened. This often leads to smaller pipes and cost savings on the domestic end. If storm water is also recycled in conjunction with plumbing fixture waste, a significant portion of a building's water requirements--up to 50 percent--can be met.

High efficiency motors

Another way facilities can save on energy cost is by using motors that are classified as NEMA Premium-Efficiency. These motors are from 0.5-4% more efficient than the EPAct motors they replace. Studies show that for retrofit and new applications, the initial motor cost is more than offset by the energy savings by adding NEMA Premium-Efficiency motors.

In addition, NYSERDA offers rebates for using NEMA Premium-Efficiency motors, further increasing the savings. In conjunction with specifying NEMA Premium-Efficiency motors is the use of variable speed drives. These save money by slowing down a pump or fan, based on the load. NYSERDA also gives rebates for using variable speed drives. The most common technique for varying motor speed is the frequency drive, or VFD. Recent improvements in integrated circuits have made VFDs smaller, cheaper and more reliable.

Ecologically friendly materials--renewables

A growing aspect of design is the use of ecologically friendly and rapidly renewable materials. Rapidly renewable materials include bamboo and cork floors, wheatgrass cabinets, sunflower seed board, cotton batt insulation and wool carpet. These materials can be grown quickly and require significantly less land to produce than other materials. This leads to cost savings for these material types.

Geothermal Heat Pump 

Instead of using fossil fuels to produce heat, heat pumps take advantage of the ground temperature, which remains relatively constant year round, to provide space heating and cooling. Geothermal heat pumps are environment-friendly because they use a series of plastic pipes buried in the ground (adjacent to the building) to circulate a glycol mixture that absorbs heat (in the winter) or rejects heat (in the summer). In addition to space heating and cooling, geothermal heat pumps can provide domestic hot water when the system is operational. Excess heat from the heat pump's compressor(s) can be recovered and transferred to the buildings hot water tank.

Using a geothermal heat pump system offers the following advantages: higher coefficients of performance, the lowest greenhouse gas emissions, minimize ozone layer damage by using less refrigerant than conventional air conditioners and by using factory-sealed refrigeration systems (which avoids potential leaks), reduce the amount of mechanical space required (one piece of equipment can provide space heating and cooling, large and potentially noisy equipment such as cooling towers, chillers and/or condensing units are eliminated).

Displacement Ventilation

Conventional Air Conditioning systems supply and return air at the ceiling level. This type of design is not ideal because air is supplied at a relatively high velocity, and at a temperature of about 20[degrees]F below the desired room temperature.

Ventilation displacement, however, locates supply air diffusers at the bottom of the occupied space. The air then travels upward through the occupied space and is exhausted and/or returned to the system by the return grills located in the ceiling.

Displacement ventilation systems are typically more energy efficient and quieter than conventional overhead systems. Supply air can be introduced to the space warmer (typically at 62-64[degrees]F) since the diffusers are located in the occupied zone, and heat generated by ceiling level lights is removed, and thus is not included when estimating building cooling loads. They also provide better ventilation efficiency, and thus improve indoor air quality.

Indoor air quality/Carbon Dioxide CO2 monitoring

ASHRAE Standard 62-1999 (Ventilation for Acceptable Indoor Air Quality) and approved Addenda provides the minimum values for ventilation rates. Optimal IAQ reduces potential liability for Engineers and Architects, and improves occupant productivity and comfort.

In the design process, indoor air quality standards should be established: fresh air intakes should be installed at least 25 feet away from exhaust points (including loading area, sanitary vents, parking garage etc).

JOSEPH TAGLIAFERRO, P.E., ASSOCIATE, LEED AND BROUCK AMERGA, LEED, AMBROSINO, DEPINTO & SCHMIEDER CONSULTING ENGINEERS PC