Measured Cooling Performance and Potential for Buried Duct Condensation in a 1991 Central Florida Retrofit Home

FSEC conducted energy performance monitoring of two existing residences in Central Florida that were undergoing various retrofits. These homes were occupied by FSEC researchers and were fully instrumented to provide detailed energy, temperature, and humidity measurements. The data provided feedback about the performance of two levels of retrofit in two types of homes in a hot-humid climate. This report covers a moderate-level retrofit and includes two years of pre-retrofit data to characterize the impact of improvements. The other home is a 'deep energy retrofit' (detailed in a separate report) that has performed at near zero energy with a photovoltaic (PV) system and extensive envelope improvements

Efficient Multifamily Homes in a Hot Humid Climate by Atlantic Housing Partners

With assistance from the Florida Solar Energy Center (FSEC) and its Building America Partnership for Improved Residential Construction (BA-PIRC), Atlantic Housing Partners (AHP) has implemented a high performance, systems engineered package of measures. This report demonstrates how the initiative achieves Building America (BA) goals of 30%-50% energy savings. Specifically, the goals are documented as being achieved in the new construction multifamily housing sector in the hot humid climate. Results from energy modeling of the high performance package are presented. The role of utility allowance calculations, used as part of the low-income housing tax credit process, to value those energy savings is discussed, as is customer satisfaction with heat pump water heaters

Performance and Impact from Duct Repair and Ventilation Modifications of Two Newly Constructed Manufactured Houses Located in a Hot and Humid Climate

Two nearly identical houses situated next to each other in Bossier City, Louisiana were studied in an effort to better understand moisture and cooling energy related problems in manufactured houses with low thermostat set-points during the cooling season. By design, the major difference between houses was the type of air conditioning units. House A had a standard split air conditioner and House B had a twospeed split air conditioner. In an effort to make the buildings more similar, the building airtightness was adjusted until it was the same in each house, and duct leaks were sealed so that the ducts were tight and there was equal tightness in both houses. A ventilation system was also added at the same time of duct repair. Duct repair and the ventilation modifications resulted in significant impacts on the cooling energy, temperature, relative humidity, and building pressures. Cooling energy decreased 37% in House A and 18% in House B, while the floor space dewpoint increased significantly. It is estimated that 35 % savings was due solely to duct repair in House A and 17% in House B. The primary cause of House A savings being twice House B is attributed to House A operating at nearly twice the capacity most of the time and had more duct leakage repaired. This resulted in higher system pressures and therefore greater duct leakage than in House B. Before building modifications, House A used 15.4 kWh per day (32%) more than House B and 3.4 kWh per day (11%) more after modifications. A method of characterizing interstitial spaces using dewpoint measurement is presented and shows that the belly space became 2.6 times more like outdoor conditions after repairs in House A and 2.0 times more in House B

Investigation of Cooling and Dehumidification Energy Use and Indoor Thermal Conditions in Polk County Schools Permanent Replacement Classroom Buildings

Increasing enrollment in grades K-12 coupled with the spiraling costs of construction has pushed school boards to develop more cost-effective classrooms, from the perspective of initial cost, longterm energy consumption, and ease of maintenance. To this end, the Florida's Polk County School Board has developed a four-quad permanent replacement classroom building. Each classroom is equipped with a package terminal heat pump (PTHP) with a thermostat control with a four-hour crank timer. The objective of this research was to compare the energy consumption and interior conditions of the autoclaved aerated concrete (AAC) construction with an unvented roof assembly to that of the conventional metal framing and concrete panel buildings. Four buildings, 2 metal-framed and 2 AAC buildings with dehumidifiers were chosen for extensive testing and monitoring. The goal was to maintain a relative humidity of 50% as well as an interior temperature of 75oF

Green and High Performance Factory Crafted Housing

In the U.S., factory-built housing greater than 400 square feet is built either to the U.S. Department of Housing and Urban Development (HUD) code for mobile homes or site-built codes for modular housing. During the last few years, as the production of HUD code housing has dwindled, many leading edge factory builders have started building modular homes to compete with site-built housing and stay in business. As part of the Building America Industrialized Housing Partnership (BAIHP) we have assisted in the design and construction of several “green” and high performance modular homes that Palm Harbor Homes, Florida Division (PHH) has built for the International Builders’ Show (IBS) in 2006, 2007, and 2008. This paper will summarize the design features and the “green” and energy-efficient certification processes conducted for the 2008 show homes, one of which received the very first E-Scale produced by BAIHP for the U.S. Department of Energy (DOE) Builders Challenge program

Achieving Airtight Ducts in Manufactured Housing

This Florida Solar Energy Center (FSEC) study, conducted under the auspices of the U.S. Department of Energy's Building America Industrialized Housing Partnership (BAIHP), compares mastic sealed duct systems to tape sealed systems by showing measured total duct leakage (CFM25TOTAL and QnTOTAL) and/or measured leakage to the outside (CFM25OUT and QnOUT) in 190 manufactured home floors or home sections. All manufacturers were considering or actively working toward achieving duct leakage below 3% of the conditioned floor area (QnOUT=0.03), consistent with Energy Star Manufactured Homes criteria. Previous field tests suggest that CFM25OUT accounts for about half of CFM25TOTAL. These data show that achieving CFM25TOTAL=6% during production was generally correlated with achieving CFM25OUT=3% in mastic sealed systems, but less reliably with taped systems. Cost for achieving duct tightness goals range from $4 to$8 including duct testing on the assembly lin

Measured Cooling Performance of Two-story Homes in Dallas, Texas; Insulated Concrete Form Versus Frame Construction

Four occupied homes near Dallas, Texas were monitored to compare heating and cooling energy use. Two homes were built with typical wood frame construction, the other two with insulated concrete form (ICF) construction. Remote data loggers collected average hourly indoor and outdoor temperature, relative humidity, furnace runtime fraction, total building electrical energy and HVAC energy use. The loggers recorded data from November 1999 through August 2000. Results show that insulated concrete form construction can reduce cooling energy use 17 to 19% in two-story homes in the north Texas climate. Two adjustments to the measured data were made to compensate for differences between the homes: (1) cooling energy use was normalized to remove the impact of miscellaneous energy use that introduces heat into the home (e.g. lights & appliances), and (2) duct leakage differences simulated in a DOE2-based software reduced the measured savings for ICF construction by 4%. Other differences noted between the homes that were not quantified included occupant impacts, exterior wall color (or absorptance) and an attic radiant barrier absent in one of the homes

Surface Deformations as Indicators of Deep Ebullition Fluxes in a Large Northern Peatland

Peatlands deform elastically during precipitation cycles by small (+/- 3 cm) oscillations in surface elevation. In contrast, we used a Global Positioning System network to measure larger oscillations that exceeded 20 cm over periods of 4 - 12 hours during two seasonal droughts at a bog and fen site in northern Minnesota. The second summer drought also triggered 19 depressuring cycles in an overpressured stratum under the bog site. The synchronicity between the largest surface deformations and the depressuring cycles indicates that both phenomena are produced by the episodic release of large volumes of gas from deep semi-elastic compartments confined by dense wood layers. We calculate that the three largest surface deformations were associated with the release of 136 g CH4 m(-2), which exceeds by an order of magnitude the annual average chamber fluxes measured at this site. Ebullition of gas from the deep peat may therefore be a large and previously unrecognized source of radiocarbon depleted methane emissions from northern peatlands