P3. Residential Hydronic System Demonstration > Conclusions

Conclusions:

Commercialization potential:

There are currently 54 member firms of the Radiant Panel Association in California and the market penetration for radiant heating with hydronic distribution is small, probably under 1%. Since it is difficult to retrofit hydronic distribution in slab-on-grade construction, this technology is likely to gain market penetration only in new construction.

Recommendations:

Results of the project should be published in construction trade journals, energy-related engineering magazines and home improvement magazines.

Both the radiant cooling using hydronic distribution and the night ventilation technologies could be promoted by utilities as means of shifting loads from on-peak to off-peak periods.

Additional research should be focused on thermal comfort aspects of radiant floor slab cooling, since the limited testing performed under this project showed that it is possible to maintain comfort, but the range of settings and conditions should be investigated further.

Benefits to California:

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:

Updated Baseline:

Electrical energy used in California residences in Year 2000 was 77,633 GWh, of which HVAC accounted for 9,610 GWh. HVAC also accounted for 7475 MW of 17,221 MW total demand in 1999. The energy used in residences for cooling (including fans) is about 56% of the HVAC total, or 5382 GWh. The peak demand due to residential HVAC is 7475 MW. Assuming that compressors and fans account for 90% of this peak demand, the cooling end use accounts for an estimated 6727 MW.

Updated Outcome:

Assuming new residential construction is adding 227,000 homes per year, or roughly 2% of 11.3 million homes existing in Year 2000 by 2015 radiant cooling could save about 0.6 GWh and 0.7 MW annually. This is based on assuming that radiant cooling is installed in 1% of these new units in the first 5 years and is installed in 2% of new homes after that, and that the technology will save 20% of cooling energy and demand.

Although the focus of the project was on radiant cooling and heating, night ventilation was tested in conjunction with radiant cooling and conventional forced air distribution. Night ventilation also showed promise as means of shifting peak demand, particularly in conjunction with radiant cooling. Night ventilation systems could also be retrofitted into existing units. The chief saving from night ventilation was shifting demand to off-peak hours. Assuming similar growth rates (1% for five years and 2% thereafter) for new and existing construction and assuming a 50% reduction in peak demand, demand reduction would be about 3.6 GW by 2015.