Computer system for energetic diagnoses in residential customers
Abstract A computerized system that carries out both energy efficiency diagnoses and cost/benefit analyses for energy efficiency measures is described. The Mexican agency, FIPATERM, provides soft financing for residential customers who participate in demand side management (DSM) programmes. Current FIPATERM programmes are: thermal insulation, substitution of the current airconditioning system by an efficient one, infiltration reduction, levelled annual payment plan, and interruption of the airconditioning equipment during peak demand hours. The residential customers who want to participate in one or several energy efficiency programmes, must agree to an energy efficiency diagnosis. Then, from both, house construction characterization and a customer equipment operation survey, the simulator allows some of the most profitable DSM measures to be identified.
A procedure for testing the ability of whole building energy simulation programs to thermally model the building fabric
A procedure was developed for systematically testing whole building energy simulation models and diagnosing the sources of predictive disagreements. Field trials of the method were conducted with a number of detailed state-of-the-art programs by researchers from nations participating in International Energy Agency (IEA) Task 12 and Annex 21. The technique consists of a series of carefully specified test case buildings that progress systematically from extremely simple to relatively realistic. Output values for the cases, such as annual loads, annual maximum and minimum temperatures, peak loads, and some hourly data are compared, and used in conjunction with diagnostic logic to determine the algorithm responsible for prediction differences. The more realistic cases, while geometrically simple, test the ability of the programs to model such combined effects as thermal mass, direct solar gain windows, window shading devices, internally generated heat, infiltration, sunspaces, earth coupling, and deadband and setback thermostat control. The more simplified cases facilitate diagnosis by allowing excitation of particular heat transfer mechanisms. The procedure was very effective at revealing bugs, faulty algorithms, and input errors in a group of building energy simulation programs that may be considered among the world`s best. The output data from the simulation programs can be usedmore » as reference ranges for comparing and diagnosing other detailed or simplified design tools.« less
Measured savings and cost-effectiveness of conservation retrofits in commercial buildings
In this study, we examine the measured saving and cost-effectiveness of 447 commercial retrofit projects, representing over 1700 buildings. Topics include saving and cost-effectiveness by building type and retrofit strategy, savings from individual measures, peak electric demand savings, comparisons of measured vs predicted savings, the persistence of savings in the year following a retrofit, and retrofit performance by year of installation. Median annual site energy savings amounted to 20 kBtu/ft{sup 2}. Median pre-retrofit energy intensity, for all building types in the data base, was higher than that of the corresponding US stock. Changes to the HVAC system were the most popular retrofit strategy, installed in 85% to 95% of the projects in each building category (education, health, office, retail, and other). Projects in which only maintenance practices were changed typically saved 12% of their pre-retrofit consumption often using in-house labor. Projects sponsored by the Institutional Conservation Program (ICP) included more shell measures (with long payback times) and relatively fewer HVAC and lighting retrofits than projects paid for by the building owner; for the buildings in this data set, retrofits installed after 1983 had lower savings, higher costs, and longer payback times than measures installed earlier. Very few predictions of savingsmore » (about one in six) came within 20% of measured results. Over half of our projects had multiple years of post-retrofit data; energy use continued to decrease for most of these buildings. Our research suggests that, despite significant savings and short payback times for the majority of projects, savings often fall well short of economically optimum levels. 28 refs., 8 figs., 5 tabs.« less