Appendix B: UCF Housing Constructability Lab Annual Report

Progress Report: April 2003 – March 2004

Prepared for:

The Industrialized Housing Partnership
&
The Building America Program

Sponsored by:

U.S. Department of Energy

Prepared by:

UCF Housing Constructability Lab
Dr. Michael A. Mullens, PE

June 15, 2004

Executive Summary

UCF researchers continue to identify and develop prototype applications of computer technology for the modular factory floor. Research efforts this year focused on real time production labor data collection. While labor represents a relatively modest fraction of production cost, typically 10-15%, it has a profound impact on operations, including product quality, cycle time, material waste, and labor productivity. The Status Tracking and Control System (STACS) is a real time shop floor labor data collection and reporting system. Production workers use wireless laser scanners to report their current work assignment. STACS reporting is web based and provides both real time manufacturing status and summaries of historical production performance.

An alpha prototype of STACS was tested in drywall finishing operations at Avis American Homes (Avis, PA) in Summer 2003. Test results demonstrated that production workers could operate the system effectively and that the system accurately captured scanned activity. Large scale plant-wide testing began at Penn Lyon Homes (Selinsgrove, PA) in March 2004 and will continue into Summer 2004. Test results will be used to develop labor models using linear regression and neural nets.

Trinity Construction Corporation is a large shell contractor serving Florida homebuilders. Faced with increasing demands for higher quality, lower cost and more timely delivery, Trinity is actively exploring innovative alternatives to conventional concrete block construction, the predominant homebuilding technology in the central and south Florida market. Trinity operates a pre-cast concrete panel production facility, in South Bay, Florida where concrete panels are pre-cast , transported to the construction site, and quickly assembled using a construction crane. The UCF Housing Constructability Lab (HCL) was asked to assist Trinity in improving the current panelizing process by incorporating lean production principles.

Preliminary research determined that material handling and rework were primary contributors to the 47% of labor consumed by non-value added activities. Once started, the flow of value-added activity was routinely interrupted. Poor access to materials and tools, rework, ill-defined process flows, and workforce/1 st line supervision issues were contributing factors. To address these issues, HCL researchers utilized lean production principles - challenging non-value added activities and removing the obstacles to continuous production flow. Recommendations addressed issues of organization/communication, structured procedures and work flow, material handling, and off-line sub-assembly.

To test the recommendations, Trinity allowed HCL researchers to perform a 3-day pilot test. The test involved a single house consisting of 25 wall panels with a gross wall area of 3,119 ft 2. Productivity increased for all observed activities, with an average increase of 68%. Not all recommendations could be realized during the test. Some equipment and personnel issues could not be resolved on a short-term test basis. This suggests that the true potential is significantly greater than that observed during the test – possibly approaching 200% increase in labor productivity. Corresponding cycle time reductions are estimated to be 20-25%. This successful pilot test has given Trinity the opportunity to develop a competitive advantage in the housing construction market and a good foundation to dominate it.

Innovative Applications of Computer Technology on the Factory Floor

UCF researchers continue to identify and develop prototype applications of computer technology for the modular factory floor. Research efforts this year focused on the collection of real time production labor data. While labor represents a relatively modest fraction of production cost, typically 10-15%, it has a profound impact on operations. Except for the slower winter months, experienced labor is a scarce resource. Even if labor is sufficient in the aggregate, it is rarely positioned where it is most needed at a particular moment in time. Competitive market pressures are resulting in an increasing mix of custom home features, increasing the likelihood of “floating bottlenecks” in production. Quality and safety can suffer as undermanned crews rush to complete custom features (i.e., fire-rated walls or a hip roof). If a crew cannot keep pace, the line slows, production rate drops, overtime is required and delivery dates are missed.

In the past, the sheer number of production activities, lengthy cycle times and extensive product customization have discouraged manufacturers from accurately estimating labor needs and using this information to plan and control production. Instead, they have responded by controlling labor at the overall plant level, attempting to maintain labor at a historical target value, which is stated as a percentage of overall production cost or sales revenue. A limitation of this approach is that it seldom reflects the actual labor content in the product, particularly in periods of increasing customization. To address the problem of shifting bottlenecks, many manufacturers use flexible resources termed “utility workers”, “flex workers”, or expeditors. However, the decision to deploy these workers is often made with minimal planning, after a problem has started to impact the line.

To better understand the true usage of production labor, the UCF research team has developed the Status Tracking and Control System (STACS). STACS is a real time labor data collection and reporting system designed specifically to meet the needs of the industrialized housing industry. A schematic of the STACS system is shown in Figure B1.

Figure B1 Structure of STACS system

Production workers use wireless laser scanners to report their current work assignment. Scanned information is transmitted immediately to a base station and then relayed to a local shop floor processor, where it is verified and temporarily staged. Information is periodically transmitted via wireless LAN to a central database server where it is stored and used for reporting. STACS reporting is web based and provides both real time manufacturing status and summaries of historical production performance. Real time production performance can be monitored from the web-based STACS Dashboard (Figure B2).

Figure B2 STACS real-time dashboard

“Clicking” on any item on the Dashboard will display corresponding real-time details. Historical results can be used for a variety of analytical and management purposes:

• The development of analytical labor estimating models. These models can be used to estimate labor requirements for product costing, production scheduling and labor planning.
• As a baseline for continuous improvement efforts.

Figure B3 Scanning drywall activities at Avis America

Lean Production of Precast Concrete Panels

Trinity Construction Corporation is a large shell contractor serving Florida homebuilders. Faced with increasing demands for higher quality, lower cost and more timely delivery, Trinity is actively exploring innovative alternatives to conventional concrete block construction, the predominant homebuilding technology in the central and south Florida market. Trinity operates a pre-cast concrete panel production facility, in South Bay, Florida where concrete panels are pre-cast (Figure B4), transported to the construction site, and quickly assembled using a construction crane (Figure B5). The UCF Housing Constructability Lab (HCL) was asked to assist Trinity in improving the current panelizing process by incorporating lean production principles.

Figure B4 Panel forms on forming bed	Figure B5 Setting pre-cast concrete wall panel

Preliminary research involved extensive observation and analysis. Value stream mapping identified activities that contributed value to the customer as well as activities that added little or no value. Material handling and rework were primary contributors to the 47% of labor consumed by non-value added activities. Once started, the flow of value-added activity was routinely interrupted. Poor access to materials and tools, rework, ill-defined process flows, and workforce/1 st line supervision issues were contributing factors. To address these issues, HCL researchers utilized lean production principles - challenging non-value added activities and removing the obstacles to continuous production flow. Recommendations addressed issues of organization/communication, structured procedures and work flow, material handling, and off-line sub-assembly. A typical recommended daily production flow is shown in Figure B6.

Figure B6 Summary of typical daily production schedule using continuous flow

To test the recommendations, Trinity allowed HCL researchers to perform a 3-day pilot test. The test involved a single house consisting of 25 panels. The panels had a total of 21 window and door openings and a gross wall area of 3,119 ft 2. The first day was spent organizing and training the test production team and the second and third days were dedicated to production. All 25 panels were produced. Productivity increased (Table B1) for all observed activities. Lifting productivity was not observed. Conservatively assuming that lifting will remain at historical levels, overall labor productivity increased by 47%. If lifting productivity is assumed to increase at the average rate observed for the other activities, overall productivity would increase 68%. Not all recommendations could be realized during the test. Some equipment and personnel issues could not be resolved on a short-term test basis. This suggests that the true potential (Table B1) is significantly greater than that observed during the test – possibly approaching 200% increase in labor productivity. Corresponding cycle time reductions are estimated to be 20-25%.

The HCL research team recommended that Trinity proceed with implementation of the lean production recommendations. In addition to the technical recommendations, the research team also made recommendations involving worker empowerment, dealing with the heat and sun, and material/equipment availability. Potential future research areas include covers for the production area, on-site factories in new home developments, and factory installed wall insulation. This successful pilot test has given Trinity the opportunity to develop a competitive advantage in the housing construction market and a good foundation to dominate it.

Publications and Presentations

Mullens, M. and M. Kelley, “Lean Homebuilding Using Modular Technology,” Housing and Society: Journal of the Housing Education and Research Association. In Press

Mullens, M. and M. Hastak, “Defining a National Housing Research Agenda: Construction Management and Production” Proceedings of the NSF Housing Research Agenda Workshop, Feb. 12-14, 2004, Orlando, FL. Eds. Syal, M., Mullens, M. and Hastak, M. Vol 2.

Mullens, M. “Production flow and shop floor control: Structuring the modular factory for custom homebuilding” Proceedings of the NSF Housing Research Agenda Workshop, Feb. 12-14, 2004, Orlando, FL. Eds. Syal, M., Mullens, M. and Hastak, M. Vol 2.

Mullens, M. and I. Nahmens, “Lean Principles Applied to Pre-cast Concrete Homebuilding,” Industrial Engineering Research ‘04 Conference Proceedings, Houston, May, 2004.

Elshennawy, A., M. Mullens, I. Nahmens, “Quality-Based Compensation Schemes for Modular Homebuilding,” Industrial Engineering Research ‘04 Conference Proceedings, Houston, May, 2004.

Nahmens, I., M. Mullens and A. Elshennawy, “The Impact of Demographics on New Homebuyer Satisfaction,” Industrial Engineering Research ‘04 Conference Proceedings, Houston, May, 2004.

Broadway, R. and M. Mullens, “Shop Floor Information Systems for Industrialized Housing Production,” Industrial Engineering Research ‘04 Conference Proceedings, Houston, May, 2004.