**6.4 Hawaii Gateway Energy Center**

The center is located on the island of Hawaii and is used by the Natural Energy Laboratory of Hawaii. The center is used for energy and technology research and development. The center is shown in **Figure 13**.

**57**

**7. Conclusions**

**Figure 14.**

*Hawaii Gateway Center radiant roof system.*

*Net-Zero Energy Buildings: Principles and Applications DOI: http://dx.doi.org/10.5772/intechopen.92285*

prompted lights to be off 100% during daylight hours.

which resulted in excess energy from the photoelectric system.

Natural ventilation is used through copper roof that radiates heat from the sun into a ceiling plenum as shown in **Figure 14**. Fresh outdoor air is pulled through the natural ventilation process into the occupied space from a vented underfloor plenum. Seawater at around 45 F (7.2°C) is used to cool the air to 72 F (22.2°C) as shown in **Figure 14**. As with the Leopold Legacy Center, the building is properly oriented to benefit from daylighting that aids lighting and reduces the energy needed to light the interior of the building. In summer, to prevent the negative affect of solar heat gain, shades are used on all windows. The center uses photoelectric daylight sensors to control the lights in addition to occupancy sensors. This

The building has 20-kW photovoltaic array which produces approximately 25,000 kW-hr due to high insolation in the area. Part of this power is used to power the pumps that draw seawater to cool the air and power the lights and other auxiliary electrical equipment. The building itself consumes 20% of the energy that comparable buildings use. In 2006, adjustments were made to the pumping systems

This chapter reviewed various techniques and designs that help achieve a netzero energy building. The most important techniques are optimizing HVAC designs to reduce energy consumptions and usage of renewable sources. Some of the techniques include geothermal heat pumps, underfloor air distribution, radiant floor heating and cooling, retractable external blind on windows, and proper orientation of the building which would maximize heat gains in cold weather and minimize it in summer using trackable blinds, photoelectric daylight sensor, and occupancy sensor. Renewable sources include fuel and biomass cells, biogas, photovoltaic cells, and EPA wood stove for heating. Water usage as well could be optimized by using gray water reclamation and by using rainwater-to-potable live water systems.

Net-zero energy building design starts with ethical clients and demonstrators. Designers and users need to be lean in their designs to reduce the energy consumption, be clean by using energy-efficient utilities and systems, and be green by using renewable energy sources such as biomass, wind, solar, geothermal heat sink, and rivers. Canals could be a good source for heat pumps in cold weather regions [22]. Future buildings will focus more on renewable and sustainable energy resources by implementing an efficient building envelope and utilizing energy-efficient and

**Figure 11.** *Photovoltaic cells used for the Aldo Leopold Legacy Center project [21].*

**Figure 12.**

*Window orientation used to aid heating and lighting in the Aldo Leopold Legacy Center [21].*

**Figure 13.** *Hawaii Gateway Energy Center [20].*

*Net-Zero Energy Buildings: Principles and Applications DOI: http://dx.doi.org/10.5772/intechopen.92285*

*Zero-Energy Buildings - New Approaches and Technologies*

*Photovoltaic cells used for the Aldo Leopold Legacy Center project [21].*

*Window orientation used to aid heating and lighting in the Aldo Leopold Legacy Center [21].*

**56**

**Figure 13.**

**Figure 11.**

**Figure 12.**

*Hawaii Gateway Energy Center [20].*

**Figure 14.** *Hawaii Gateway Center radiant roof system.*

Natural ventilation is used through copper roof that radiates heat from the sun into a ceiling plenum as shown in **Figure 14**. Fresh outdoor air is pulled through the natural ventilation process into the occupied space from a vented underfloor plenum. Seawater at around 45 F (7.2°C) is used to cool the air to 72 F (22.2°C) as shown in **Figure 14**. As with the Leopold Legacy Center, the building is properly oriented to benefit from daylighting that aids lighting and reduces the energy needed to light the interior of the building. In summer, to prevent the negative affect of solar heat gain, shades are used on all windows. The center uses photoelectric daylight sensors to control the lights in addition to occupancy sensors. This prompted lights to be off 100% during daylight hours.

The building has 20-kW photovoltaic array which produces approximately 25,000 kW-hr due to high insolation in the area. Part of this power is used to power the pumps that draw seawater to cool the air and power the lights and other auxiliary electrical equipment. The building itself consumes 20% of the energy that comparable buildings use. In 2006, adjustments were made to the pumping systems which resulted in excess energy from the photoelectric system.
