Robert Hendron

Development of Standardized Domestic Hot Water Event Schedules for Residential Buildings

The Building America Research Benchmark is a standard house definition created as a point of reference for tracking progress toward multi-year energy savings targets. As part of its development, the National Renewable Energy Laboratory has established a set of domestic hot water events to be used in conjunction with sub-hourly analysis of advanced hot water systems.

Thermal Performance of Unvented Attics in Hot-Dry Climates: Results from Building America

Unvented attics have become a more common design feature implemented by Building America partners in hot-dry climates of the United States. More attention is being focused on how this approach affects heating and cooling energy consumption. By eliminating the ridge and eave vents that circulate outside air through the attic and by moving the insulation from the attic floor to the underside of the roof, an unvented attic become a semi-conditioned space, creating a more benign environment for space conditioning ducts.

Potential for Energy Savings Through Residential Hot Water Distribution System Improvements

Hot water distribution systems have received a great deal of attention recently, as residential energy efficiency programs target measures that can drive whole-house energy savings beyond the 50% level. Unfortunately, evaluating distribution losses and the resulting thermal interactions with space conditioning loads is very complicated, and must be performed using advanced simulation tools and realistic hot water event schedules, including appropriate event volumes, draw sequencing, and time between draw events. The authors developed a simplified methodology for the analysis of distribution losses based on detailed modeling of alternative system designs using HWSIM, a model specifically designed for this application. Curve fits were then applied to the results so they could be extrapolated to many different house designs and climate regions. The authors also performed preliminary analysis of whole house energy effects of alternate hot water distribution systems in two climates.

Evaluation of a High-Performance Solar Home in Loveland, Colorado

Building America (BA) partner McStain Neighborhoods built the Discovery House in Loveland, Colorado, with an extensive package of energy-efficient features, including a high-performance envelope, efficient mechanical systems, a solar water heater integrated with the space-heating system, a heat-recovery ventilator (HRV), and ENERGY STAR™ appliances. The National Renewable Energy Laboratory (NREL) and Building Science Consortium (BSC) conducted short-term field-testing and building energy simulations to evaluate the performance of the house. These evaluations are utilized by BA to improve future prototype designs and to identify critical research needs. The Discovery House building envelope and ducts were very tight under normal operating conditions. The HRV provided fresh air at a rate of about 75 cfm (35 l/s), consistent with the recommendations of ASHRAE Standard 62.2. The solar hot water system is expected to meet the bulk of the domestic hot water (DHW) load (>83%), but only about 12% of the space-heating load. DOE-2.2 simulations predict wholehouse source energy savings of 54% compared to the BA Benchmark [1]. The largest contributors to energy savings beyond McStain’s standard practice are the solar water heater, HRV, improved air distribution, high-efficiency boiler, and compact fluorescent lighting package.

Field test of room-to- room uniformity of ventilation air distribution in two new houses

In order for dilution ventilation systems to provide predictable results independent of the geometry of individual homes, outside air must be uniformly distributed throughout the house. The primary purpose of this field test was to characterize the uniformity of room-to-room ventilation air distribution under various operating conditions by examining multi-zone tracer gas decay curves and calculating local age-of-air. The tests were conducted in two Sacramento houses, and were designed to allow direct, quantitative comparisons of various ventilation approaches, which could potentially be factored into ventilation rate trade-offs in future updates to ASHRAE Standard 62.2. We observed the effects of providing single-point exhaust ventilation versus central-fan-integrated supply ventilation, and the

Thermal Performance of Unvented Attics in Hot-Dry Climates: Results From Building America

As unvented attics have become a more common design feature implemented by Building America partners in hot-dry climates of the United States, more attention has been focused on how this approach affects heating and cooling energy consumption. By eliminating the ridge and eave vents that circulate outside air through the attic in most new houses and by moving the insulation from the attic floor to the underside of the roof, an unvented attic becomes a semiconditioned space, creating a more benign environment for space conditioning ducts. An energy trade-off is made, however, because the additional surface area (and perhaps reduced insulation thickness) increases the building loss coefficient. Other advantages and disadvantages, unrelated to energy, must also be considered. This paper addresses the energy-related effects of unvented attics in hot-dry climates based on field testing and analysis conducted by the National Renewable Energy Laboratory.Copyright

Evaluation of a High-Performance Multifamily Residential Building in Aspen, Colorado

Multifamily housing is an essential component of urban sustainable design, because finite available urban space necessitates greater use of attached housing and shared community spaces. Improving the energy efficiency of this category of housing presents special challenges, because units share walls and the space heating and domestic hot water systems are frequently centralized, requiring recirculation and long pipe runs to reach all units. These challenges were investigated as part of the first phase of a high-performance multifamily housing community called Burlingame Ranch in Aspen, Colorado. The first phase of the project has been completed, and features such energy efficiency measures as insulated slab-on-grade foundations, condensing boilers, solar preheat for hot water, heat recovery ventilation, and energy-efficient lighting and appliances. The authors participated in a thorough evaluation of key building systems for one prototype building and provided insights into potential design improvements that can be implemented in the second phase of construction.© 2009 ASME

Field Evaluation of a Near Zero Energy Home in Oklahoma

The authors evaluated a Zero Energy Home (ZEH) built by Ideal Homes in Edmond, Oklahoma, that included an extensive package of energy-efficient technologies and a photovoltaic (PV) array for site electricity generation. The ZEH was part of a Building America (BA) research project in partnership with the Building Science Consortium to exhibit high efficiency technologies while keeping costs within the reach of average home buyers, and was a modified version of a production 1584-ft2 , three-bedroom, single-story, slab-on-grade design with attached garage. The home included a tight, well-insulated envelope, an energy recovery ventilator, high-performance windows, tankless gas water heater, efficient lights and appliances, and a ground source heat pump (GSHP). We conducted a series of short-term tests beginning in August 2005, and have collected long-term data under occupied conditions since February 2006. The GSHP performance was disappointing until the outdoor unit was replaced, after which time the efficiency began to meet expectations. However, the electricity use of the replacement unit was higher than expected because of an unusually low cooling setpoint. Based on the measured test results, the predicted whole-house energy savings compared to the BA Benchmark was 96%, with savings of 55% for efficiency measures alone.Copyright