**6.2 La Jolla Commons**

La Jolla Commons II is a 13-story office at the University Town Center which is considered to be one of the largest NZEB in the United States. The building has a total area of 415,000 ft<sup>2</sup> (38,555 m2 ) and was completed in April 2014 in San Diego, California. The completed building is shown in **Figure 6**. The building is rated as pre-certified silver as per US Green Building Council and a potential building for LEED platinum. The building has slab on-grade foundation. Other sustainability features include low-emissive coatings that reflect invisible long-wave infrared (IR) heat, reduce heat gain or loss in the building, and provide greater light transmissions. The walls were all glass as shown in **Figure 6** [18]. The air was supplied through underfloor air distribution (UFAD) system at 68 F (20°C). The cooling loads were 15 tons per floor and were supplied through two 560 tons cooling towers that served chillers located in the basement of the building. To achieve the net-zero energy efficiency, the building reduced the consumption through efficient designs and sustainable practices in addition to on-site generation. Fuel cells were generated at a rate of 5.4 megawatt-hour, whereas the historical expected consumption was approximately 4.5 megawatt-hour. The fuel cell technical data are shown in **Table 1**. The fuel cells are shown in **Figures 7** and **8**. The building is fed by biogas which would reduce energy costs. The cost per square footage was higher but it came with more benefits.

**53**

**6.3 Aldo Leopold Legacy Center**

*Technical highlights for the La Jolla Commons fuel cells.*

tions, with over 11,900 ft<sup>2</sup>

**Inputs**

*La Jolla Commons [18].*

**Figure 6.**

**Outputs**

**Physical**

**Table 1.**

It is classified as one of the greenest buildings on the planet as depicted by the US Green Building Council Prez [19]. The project consists of three one-story buildings. The project is located in Baraboo, WI, with cold and humid air condi-

Electrical connection 480 V at 60 Hz, three- or four-wire three-phase

Size 26' 5" × 8' 7" × 6' 9" (8 m × 2.6 m × 2 m)

**Fuels Natural gas, directed biogas** Input fuel pressure 15 psi, gage (6.89 kPa, gage) Fuel required at the rated power 1.32 MMBtu/h of natural gas

Base load output (net AC) 200 kW Electrical efficiency (LHV net AC) >50%

Weight 19.4 tons

LEED-NC with net-zero energy rating. The first features of this project were the reduction in water consumption which reached up to 65% through the usage of waterless urinals, dual-flush toilets, and efficient faucets. The other features were the efficient irrigation features implemented using crushed gravels instead

). It has a platinum rating from the USGBC

area (1105 m<sup>2</sup>

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

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

**Figure 6.** *La Jolla Commons [18].*

*Zero-Energy Buildings - New Approaches and Technologies*

building in the world. It is a six-story building and has a total area of 52,000 ft2

efficiency is 83% better than a typical office in Seattle with many efficient and sustainable energy sources including a 242 kW photovoltaic array, ground source geothermal heat exchange system, radiant floor heating and cooling, and retractable external blinds that block heat from warming the building. For water usage aspect, the center is 80% more efficient than a typical office in Seattle with live rainwaterto-portable water system that can collect up to 56,000 gallons (211,948 L) of rainwater [16]. The building also uses gray water reclamation using compositing foam flush toilets that save up to 96% of water as compared to traditional flush toilets. The

La Jolla Commons II is a 13-story office at the University Town Center which is considered to be one of the largest NZEB in the United States. The building has a

California. The completed building is shown in **Figure 6**. The building is rated as pre-certified silver as per US Green Building Council and a potential building for LEED platinum. The building has slab on-grade foundation. Other sustainability features include low-emissive coatings that reflect invisible long-wave infrared (IR) heat, reduce heat gain or loss in the building, and provide greater light transmissions. The walls were all glass as shown in **Figure 6** [18]. The air was supplied through underfloor air distribution (UFAD) system at 68 F (20°C). The cooling loads were 15 tons per floor and were supplied through two 560 tons cooling towers that served chillers located in the basement of the building. To achieve the net-zero energy efficiency, the building reduced the consumption through efficient designs and sustainable practices in addition to on-site generation. Fuel cells were generated at a rate of 5.4 megawatt-hour, whereas the historical expected consumption was approximately 4.5 megawatt-hour. The fuel cell technical data are shown in **Table 1**. The fuel cells are shown in **Figures 7** and **8**. The building is fed by biogas which would reduce energy costs. The cost per square footage was higher but it came with

) and was completed in April 2014 in San Diego,

\$18.5 million which yields \$355 per square foot (per 0.09 m2

(38,555 m2

building has also green roof and wetlands.

*Seattle's net-zero energy building (Bullitt Center).*

**6.2 La Jolla Commons**

total area of 415,000 ft<sup>2</sup>

). The building is energy and carbon neutral, but its cost reaches as high as

). The center's energy

**52**

more benefits.

(4800 m2

**Figure 5.**


**Table 1.**

*Technical highlights for the La Jolla Commons fuel cells.*

#### **6.3 Aldo Leopold Legacy Center**

It is classified as one of the greenest buildings on the planet as depicted by the US Green Building Council Prez [19]. The project consists of three one-story buildings. The project is located in Baraboo, WI, with cold and humid air conditions, with over 11,900 ft<sup>2</sup> area (1105 m<sup>2</sup> ). It has a platinum rating from the USGBC LEED-NC with net-zero energy rating. The first features of this project were the reduction in water consumption which reached up to 65% through the usage of waterless urinals, dual-flush toilets, and efficient faucets. The other features were the efficient irrigation features implemented using crushed gravels instead

**Figure 7.** *Fuel cells used at the La Jolla Commons building.*

**Figure 8.** *Fuel cells used at the La Jolla Commons building.*

of blacktop or concrete paving which increased the rainwater infiltration and helped in blending the developed areas with the surrounding landscape which eliminated the need for irrigation. The utmost feature for this project was the significant reduction in energy usage which reached to 70% less than a comparable conventional building by using 39.6 kW rooftop photovoltaic arrays that produces more than 110% of the project's annual electricity needs. A sketch for the design is shown in **Figure 9**, and a picture showing the installed cells on the roof is shown in **Figures 10** and **11**.

The buildings were oriented properly to have the maximum solar radiation source. Not only ground heat pumps were used as sources for heating and cooling, but Earth tubes were used to preheat and precool ventilation air, as well. Windows were utilized and properly oriented toward the south to get the maximum daylight that can reduce heat needs and lighting. The window area was maximized to optimize these two factors as shown in **Figure 12**.

**55**

**Figure 10.**

**Figure 9.**

*Aldo Leopold Legacy Center in Wisconsin [20].*

and not the maximum designed.

**6.4 Hawaii Gateway Energy Center**

development. The center is shown in **Figure 13**.

*Photovoltaic cells used for the Aldo Leopold Legacy Center project [20].*

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

For additional heat, EPA-approved wood stove or fireplace was used. The final couple features were the usage of displacement ventilation and demand-controlled ventilation through the usage of variable frequency drives for fans that would control the amount of cooling or heating supplied to the spaces based on actual load

The payback period for this project is expected to be around 14 years [20].

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

#### **Figure 9.**

*Zero-Energy Buildings - New Approaches and Technologies*

of blacktop or concrete paving which increased the rainwater infiltration and helped in blending the developed areas with the surrounding landscape which eliminated the need for irrigation. The utmost feature for this project was the significant reduction in energy usage which reached to 70% less than a comparable conventional building by using 39.6 kW rooftop photovoltaic arrays that produces more than 110% of the project's annual electricity needs. A sketch for the design is shown in **Figure 9**, and a picture showing the installed cells on the roof is shown in

The buildings were oriented properly to have the maximum solar radiation source. Not only ground heat pumps were used as sources for heating and cooling, but Earth tubes were used to preheat and precool ventilation air, as well. Windows were utilized and properly oriented toward the south to get the maximum daylight that can reduce heat needs and lighting. The window area was maximized to

**54**

**Figures 10** and **11**.

**Figure 8.**

**Figure 7.**

*Fuel cells used at the La Jolla Commons building.*

*Fuel cells used at the La Jolla Commons building.*

optimize these two factors as shown in **Figure 12**.

*Aldo Leopold Legacy Center in Wisconsin [20].*

#### **Figure 10.**

*Photovoltaic cells used for the Aldo Leopold Legacy Center project [20].*

For additional heat, EPA-approved wood stove or fireplace was used. The final couple features were the usage of displacement ventilation and demand-controlled ventilation through the usage of variable frequency drives for fans that would control the amount of cooling or heating supplied to the spaces based on actual load and not the maximum designed.

The payback period for this project is expected to be around 14 years [20].
