P4. Design Methods and Guidelines for Natural Ventilation in California > Conclusions

Five important considerations specific to the application of natural ventilation to commercial buildings in California are climate suitability, ambient air quality, internal loads, thermal mass, and relevant codes and standards.

The coastal climates in California are very well suited for natural ventilation. The inland climates are not, but night cooling and hybrid ventilation systems would work well provided design parameters are suitable.

Application of natural ventilation to new buildings requires careful assessment of climate, occupancy, ambient air conditions, and ambient noise conditions. Natural ventilation should be used in coastal areas, but is not recommended in hot inland areas unless used in conjunction with a mechanical system (a hybrid system).

Review codes and standards to identify issues that impede application of natural ventilation.

Research the impact of other issues, such as building security and fire safety, on natural ventilation applications.

Based on new data regarding the characteristics of California building stock and statewide energy use, the projected benefits of this project are updated as follows:

Natural ventilation has the greatest potential in new construction located in coastal climates. Pacific Gas and Electric, Southern California Edison, Los Angeles Department of Water and Power, San Diego Gas and Electric, and several smaller utilities serve the California coastal climate zones (1, 2, 3, 4, 5, 6, and 7). Commercial floor area data by building type are not available by climate zone. However, using US census data and assuming that the location of commercial building space is directly proportional to population, the estimated total commercial floor area in climate zones 1 through 7 totals 1,943 million sf (based on 34% of the population in 2000 living in climate zones 1 through 7). New commercial construction for Year 2000 added about 156 million square feet. The annual growth rate in new construction is expected to range between 2.7% and 2.4% each year through 2015. Between 2001 and 2015, the total new commercial office space is estimated to be 2,444 million sf. Assuming that new construction is also proportional to population and that the coastal climate zones maintain 34% of the total population, the new construction will total 831 million sf.

Cooling and ventilation consumed 15.5% and 10.2% of 91,771 GWh used by commercial buildings in Year 2000 (1.62 kWh/sf-yr and 2.50 kWh/sf-yr, respectively). Although natural ventilation could replace both end-uses, the use of ventilation fans to also distribute heating energy means that ventilation fans are likely not to be displaced by natural ventilation design. More likely, using ventilation fans for heating distribution will encourage hybrid designs. For purposes of estimating energy savings from natural ventilation, only the cooling end use will be considered.

Early adoption of natural ventilation, or hybrid ventilation, as alternative cooling strategies is likely to be slow due to building owner and tenant perception that only mechanical ventilation is reliable and comfortable. Assuming that 1% of new construction in the coastal climate zones, or 8.3 million square feet, is designed with natural ventilation systems by 2015, the avoided cooling energy would be about 13.6 GWh/yr.

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