Gautam S. Dutt

Producer Gas Engines in Villages of Less-Developed Countries

Producer gas engines could have an important role in the decentralized production of mechanical energy in rural areas of less-developed countries. With this technology mechanical energy is produced from solid fuels by use of internal combustion engines. A comparison with other renewable energy options, on the common basis of energy efficiency and economics, shows that producer gas engines may have significant advantages and deserve serious attention.

A thermodynamic analysis of energy needs: A case study in A Mexican village

A detailed analysis of energy needs in a village is presented. Energy needs are analyzed in terms of first- and second-law efficiencies, for each conversion device and a total of 22 end uses. The first-law efficiency of the village energy system is 17%, while the second-law efficiency is only 6%. Taking into account energy losses outside the village, the efficiency of modern technologies approaches that of traditional devices. While 58% of energy needs correspond to work and heat at < 100 °C, 98.1% of the energy sources involve combustion processes (wood and petroleum) at medium to high temperatures. This mismatch between the quality of energy sources and needs shows that substantial improvements in energy efficiency are attainable.

BUILDING ENERGY USE COMPILATION AND ANALYSIS (BECA) PART B: RETROFIT OF EXISTING NORTH AMERICAN RESIDENTIAL BUILDINGS

Abstract BECA-B assesses the technical performance and economics of energy conservation retrofit measures. The data collected thus far represent measured energy savings and retrofit costs for over 65 North American residential retrofit projects. The samples size within each project ranges from individual homes to 33 000 dwellings participating in a utility-sponsored program. The median value of space heating energy savings is 24% of the pre-retrofit consumption. For fuel-heated homes, the median cost of conserved energy is

Critical significance of attics and basements in the energy balance of Twin Rivers townhouses

3.66/GJ, substantially less than the U.S. Average 1981 prices for purchased energy of

PRISM applied to a multifamily building: The lumley homes case study

4.27/GJ for natural gas and

The modular retrofit experiment: design, scorekeeping and evaluation

8.25/GJ for fuel oil. For ten of the eleven electric heat retrofits the cost of conserved electricity is less than the 1981 U.S. average price of 6.2¢/kWh.

Understanding heat loss in houses

Abstract Approximately 35% of winter energy loss in Twin Rivers townhouses is associated with the attic, despite the presence of 9 cm of fiberglass insulation. Unexpected heat transfer mechanisms bypass the attic insulation and strongly couple attic, basement and house. As a result, a three-zone model is required for static heat load calculations and the prediction of retrofit savings. Magnitudes of the unexpected heat transfer rates can be inferred from attic and basement temperatures and knowledge of furnace inefficiencies. The model predicts the benefits to be gained by various retrofit strategies. Effectiveness of retrofits may be considerably enhanced by blocking heat transfer bypass paths to the attic.

PRELIMINARY RESULTS OF THE MODULAR RETROFIT EXPERIMENT: TESTS OF THE HOUSE DOCTOR CONCEPT BY NEW JERSEY'S GAS UTILITIES

Abstract The gas consumption for space and water heating and for cooking in a multifamily building is analyzed using the Princeton Scorekeeping Method (PRISM). An objective of the study is to explain in physical terms the components of annual gas consumption, and to discuss how physical parameters and their changes can be observed in the data. The three-parameter model of PRISM is estimated using both monthly billing data and daily measurements obtained from instrumentation installed in the building. The effects on parameter estimates of known physical characteristics, namely high indoor temperatures and seasonal changes in base-level consumption, are discussed. The effects of unknown physical characteristics, namely heating system efficiency and infiltration rate, are inferred from the analysis. These variables are estimated using an extended PRISM model. We conclude that careful consideration of the buildings operation and other supplemental data permit physical interpretations of parameter estimates that are not possible with a straightforward a application of PRISM alone. Departures from the validity of the assumptions of constant base level, constant heating slope, and constant reference temperature throughout a season are examined.

The two-resistance model for attic heat flow: implications for conservation policy☆

Abstract The Modular Retrofit Experiment (MRE) was a collaboration between five gas utilities and Princeton designed to provide well documented measurements of energy savings associated with house retrofits. Two retrofit strategies were evaluated — a one-day visit by “house doctors”, using instrumented energy analysis, and the same house-doctor treatment followed by additional, major retrofits. The 138 houses in this experiment included a group of control houses that received no treatment. All three groups showed significant energy savings, measured using the Princeton Scorekeeping Method (PRISM). Median percent savings (± standard errors) for the control, house-doctor, and major-retrofit houses were 9.8 (±1.4), 15.3 (±1.9), and 21.9 (±1.2), respectively. The savings in the control group closely agree with the average gas savings in the utility service areas over the same period of time. Our analysis indicates that the full potential of the one-day house-doctor visit was not realized in the MRE. Nevertheless, estimates of costs and savings reveal that house doctoring was more cost-effective than the more conventional measures installed in the subsequent contractor retrofits.

Measurement of Air Leakage Properties of Common Residential Insulating Materials

Heat loss from houses obeys the standard physics of conductive, convective, and radiative heat transfer. However, in a real house two‐ and three‐dimensional conduction can greatly increase heat loss relative to a simple one‐dimensional model, and subtle convective phenomena can produce additional heat loss anomalies. Radiative processes can interact with conduction and convection with surprising results. Recent developments in modeling these heat transfer processes are presented in this paper. Steady state formulations are adequate for understanding elusive heat loss paths. Non‐steady‐state models permit the measurement of house heat loss from short term data and permit the characterization of transient heat flow processes. The applications of several steady and unsteady heat loss models to energy conservation problems are reviewed in this paper.