Guidelines for Measuring Air Infiltration Heat Exchange Effectiveness (IHEE), Submitted to the Texas Higher Education Coordination Board Energy Research Application Program Project #227

This report presents three methods of measuring the air infiltration heat recovery in buildings. The blower door method estimates the air infiltration heat recovery using a test which takes less than one hour, and gives information to the contractors making retrofit decisions. The co-heating method identifies the relationship between the infiltration heat recovery and the air flow rate using two or three nights of testing. This method has higher accuracy than the blower door method and is suitable for use by both contractors and researchers. Finally, the STAM (short term average method) investigates the relationship between air infiltration heat recovery and air flow rate, air flow direction, and solar radiation. This is a comprehensive method which is most suitable for use by researchers.This report is presented to the Texas Higher Education Coordination Board as a deliverable under the Energy Research and Applications Program Project #227, which targeted reducing the design size of HVAC systems in houses since the actual air infiltration energy consumption is less than the design values due to air infiltration heat recovery in house components

The Measured Energy Impact of Infiltration in an Outdoor Test Cell

The energy consumption calculation of house envelopes assumes that conduction heat loss is independent on air infiltration heat loss, and that energy consumption is the sum of these losses. Anderlind [1985], Liu [1987], and Claridge et at. [1989] showed this method can overestimate energy consumption substantially under steady-state conditions. Bailly [1987] and Anderson [1987] reported much smaller house energy consumption when the air flow was organized by mechanical systems. However, none of these studies quantified energy loss reduction under a variety of outdoor weather conditions. The energy performance was investigated in an outdoor test cell with different leakage configurations and air flow rates under both infiltration and exfiltration. It was found that the energy consumption was not only dependent on air flow rate, temperature differences, and solar radiation, but also on the air flow direction and the air leakage configuration. Infiltration could lead to a much lower heating energy consumption than that of exfiltration, and exfiltration could lead to a much lower cooling energy consumption than that of infiltration. The air infiltration energy consumption of a leaky house could be 9 times as high as that of a tight house even when the air flow rate was the same for both houses

The Measured Energy Impact of Infiltration Under Dynamic Conditions

Energy consumption due to air infiltration is customarily assumed to equal the mass flow rate times the specific enthalpy difference between the inside and outside air. Anderlind showed theoretically that this represents an upper limit for the energy impact of infiltration with an idealized steady-state wall model. Claridge and Bhattacharyya found it to be 20% to 80% of the value customarily used in an indoor test cell and a frame wall under steady-state condition. However, in real buildings, the heat transfer process is a complicated non-linear process, and neither the temperature nor the air flow rate is constant. Therefore, the validity of the steady-state methodology should be proved for dynamic condition. As a preliminary step, dynamic tests were conducted by varying an indoor test cell temperature in a periodic manner for a variety of leakage configurations and air flow rates. The measurement results demonstrated that the cell envelope can be treated as a linear system, and the steady-state methodology or time-averaging technique can be used for the treatment of energy performance when a constant air flow rate is present

An Advanced Economizer Controller for Dual Duct Air Handling Systems - with a Case Application

Heating penalty is expected when economizers are applied to dual-duct air handling systems. The heating penalty can even be higher than the cooling savings when the hot air flow is higher than the cold air flow. To avoid the excessive heating penalty, advanced economizers are developed in this paper. The application of the advanced economizer has resulted in $7,00O/yr savings in one 95,000 ft2 school building since 1993. The impacts of cold and hot deck settings on the energy consumption are also discussed

Impacts of Optimized Cold & Hot Deck Reset Schedules on Dual Duct VAV Systems - Theory and Model Simulation

Optimal hot and cold deck reset schedules can decrease simultaneous heating and cooling in VAV AHUs comparing with constant cold deck temperature operation. In this paper, optimization models are developed. The energy impacts are simulated for a typical office building in the hot and humid climate (Galveston, Texas). The simulation results show that the optimized reset schedules can reduce the cost of AHU energy consumption (cooling, heating and fan power) by 8% to 20% in normal VAV systems when the minimum air flow rate increased from 30% to 70% of the maximum flow

Potential Operation and Maintenance (O&M) Savings in the John Sealy North Building at UTMB

The LoanSTAR Monitoring and Analysis Group, Energy Systems Laboratory at Texas A&M University, was requested by University of Texas Medical Branch at Galveston to investigate O&M measures in their five LoanSTAR program buildings. This report describes the suggested O&Ms in John Sealy North Building, a surgical building of 54,494 ft2,which currently spends 502,100 per year on electricity, steam and chilled water. The suggested O&Ms include optimizing the outside air treatment cold deck reset schedule, the cold deck reset schedule and the hot deck reset schedule. These optimized HVAC operation schedules were determined using an analysis involving a simplified HVAC model, which was calibrated against daily data measured by the LoanSTAR program. It is estimated that annual savings of 67,000, or 13% of the annual costs, can be realized using the optimized operation schedules which can be implemented without additional costs. Our analysis indicates that the room comfort levels will not be degraded by these measures

A Prediction of Energy Savings Resulting from Building Infiltration Control

Heat transfer through building walls consists of three main components: conduction heat transfer, solar gain and infiltration heat transfer. An interaction among these three heat transfer components alters the effective heat transfer through a wall, working to reduce or increase it. This study uses simulation to evaluate the potential energy impact of the interaction when several different strategies for controlling air leakage direction and velocity in building envelope components are implemented. The simulations performed in this study show that significant energy savings can be realized with the use of controlled airflow through non-airtight walls in a building. Comparing the energy load of a building which uses airflow control in its walls with the energy load found with a standard calculation (where the interaction effect is not considered), annual energy load savings were found in a warm climate as high as 17%. The results were less promising when compared against the performance of a building experiencing simulated natural airflow (and heat recovery) through its exterior walls: the best annual load savings percentage was 10% in a warm climate. It was found that in a cooler climate, the natural flow configuration performed about as well as any of the artificial airflow configurations, so airflow control is not recommended in cool climates

A Report on the Environmental Impact of the Texas LoanSTAR Program from May 1989 to September 1995

There are a number of factors that influence emission factors. The three major pollutants considered in this analysis are CO2, SO2, and NOX. Emission factors from three different sources were considered for this report. This analysis shows that as of September, 1995, there has been a reduction in emissions of 1.88 million pounds of NOX, 1.19 million pounds of SO2, and 532 million pounds of CO2 through the implementation of energy conservation measures in the Texas LoanSTAR program.The Texas LoanSTAR (Loans to Save Taxes and Resources) program was created by the state of Texas in 1989 to lend money for energy conserving improvements, or retrofits, in public buildings. As of September 1995 the LoanSTAR program is measuring savings for 22 loan sites covering 153 buildings where retrofits have been fully or partially completed. The completed retrofits show $21.1 million in measured savings, which is more than 119% of the energy savings predicted by the energy auditors. This corresponds to 23.9% of the pre-retrofit consumption cost at these sites. Through energy savings, the Texas LoanSTAR program has made a significant contribution towards reducing hazardous environmental emissions

Rehabilitating A Thermal Storage System Through Commissioning

A thermal storage system was installed in a 37,000 ft2 hospital in April 1992. The chiller had to be operated every summer during peak demand periods until the authors rehabilitated system through building commissioning in late 1995. This paper presents information about the building systems, commissioning activities, and the measured energy savings which resulted from the process

Signatures of Heating and Cooling Energy Consumption for Typical AHUs

An analysis is performed to investigate the signatures of different parameters on the heating and cooling energy consumption of typical air handling units (AHUs). The results are presented in graphic format. HVAC simulation engineers can use these graphs to make quick and rational decisions during the model calibration, identify faulty parameters, and develop optimized operation and control schedules. An application example is given as well in the paper