The Department of Environmental Studies at Sonoma State University built itself an energy center in the 1970s, using student labour: this was completely rebuilt in 2000-1. The Center is located on the University campus, about 40 miles north of San Francisco.

The main space of the 2 200 sq. ft. Center is a large seminar room .This is flanked by offices and ancillary spaces.. The construction is well insulated: the walls and roof use structural insulated panels (SIPs) over a steel frame to eliminate cold bridging and minimize uncontrolled air infiltration. Thermal mass is provided internally by dense concrete block walls to the north and south of the seminar space, separating it from the subsidiary rooms, while the floor is exposed concrete. A tall panel of rammed earth separates the main space from the entrance lobby

The building is designed to minimize both heating and cooling energy use. The heating system is a hydronic loop embedded in the floor slab: hot water is pumped around this from a gas-fired boiler: however, this has been little used, due to the high insulation values of the building fabric and low infiltration rates. Additional winter heat is provided by the trombe walls located in the offices on the south side of the building. During the summertime, incoming solar radiation is blocked by external metal shades, effectively switching the trombe walls off.

Fig.6: Environmental Technology Center, Sonoma State University, Rohnert Park, California. Architect: AIM Associates.

These shading devices are also deployed in summer to minimize solar gain to the spaces on the south side of the building. A large canvas awning is similarly rolled out when required to shade the entrance lobby. The south facing clerestory window at the top of the main space has a roll down shutter which can also be used to exclude solar gain, or provide blackout when needed for lectures.

The summertime cooling strategy is thus helped by reduction in cooling load. Furthermore, night ventilation is used to cool the building, removing the heat stored in the thermally massive elements during the day. Panels in the north side of the clerestory lantern open to allow hot air out. Inlets are provided by the upper windows in the offices on the south side of the building; the lobby; and windows on the east wall.

The south side of the standing seam roof has a PV installation rated at 3kW. This is a building integrated system using amorphous silicate “stick-on” panels: all electrical connections are made within the ridge piece of the roofing system.

Potential for carbon trading

Each of the three buildings described above is expected to perform substantially better than the Californian norm (Title 24). Figure 7 shows a frequency distribution of C02 emissions due to electricity use for a sample of commercial buildings. Estimated performance by the three case study buildings is superimposed for comparison: respectively 65%, 50% and 20% of the Title 24 norm.

• monetary savings, purely in terms of avoided energy costs, can be considerable — even for buildings such as the Jasper Ridge Biological Preserve which incurred little if any additional construction costs for its energy saving features.

• recent prices for carbon are too low even, in themselves, to justify the transaction costs in entering a trading scheme [43]

the emergence of markets in futures in emission allowances. Another is the involvement of “novice” market participants. Most people, even facilities professionals, take key decisions about a relatively small number of new build projects during their careers.

Conclusion

At current values, carbon emission permits are worth little. However, this underestimates their value as financial instruments in limiting downside risk when a building owner is contemplating investment in low-energy measures.

The paper therefore concludes that carbon emission trading is a potentially valuable policy instrument in improving the uptake of energy efficiency measures in the built environment. Detailed design of policy instruments — such as the forthcoming EU-wide emission trading scheme — and co-ordination between different mechanisms, will have a vital role to play in bringing buildings to the carbon marketplace.