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The Retro Commissioning Sensor Suitcase 2022 identifies four new energy efficiency opportunities (i.e., plug load energy savings potential, improve system operation schedule, improve setbacks on nights and weekends, and peak load reduction) and this codebase identifies those opportuntiies.
Conventional wisdom surrounding space heating has consistently stated two things: size the mechanical systems to the heating loads, and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. The implication of this is that, for setback to be successfully implemented, the heating system must be oversized. This issue is exacerbated further when an outdoor reset control is used with a condensing boiler, because not only is the system matched to the load at design, the outdoor reset control matches the output to the load under varying outdoor temperatures. Under these circumstances, the home may never recover from setback. Special controls to bypass the outdoor reset sensor are then needed. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. The first step is to determine the appropriateness of setback for a particular project. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step-by-step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.
For years, conventional wisdom surrounding space heating has specified two points: size the mechanical systems to the heating loads, and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. Determining the appropriateness of setback for a particular project is the first step. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step-by-step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.
The Solar Living House is a high-performance solar-powered dwelling designed by a team of faculty and students from the University of Florida, in collaboration with Santa Fe College, the National University of Singapore, and Alachua Habitat for Humanity. The project was designed in accordance with the Solar Decathlon 2015, a research, design, education, and outreach program developed by the U.S. Department of Energy (DOE). The Solar Living House is fundamentally a house for living, centered on people and the activities of daily life while quietly introducing advanced design, construction, and engineering technologies. The 993 square-foot two-bedroom one-bath home was designed to embrace and frame an exterior courtyard space. This courtyard acts as an extension of the interior living spaces, maximizing the spatial potentials of a modest building footprint and introducing natural light into the primary living spaces of the house. Research Outcomes: The Solar Living House advances work on high-performance buildings through three principal technological innovations: wet/dry modular construction, a building automation system, and solar dehumidification systems. Wet / Dry Modular Construction: The house is designed as a series of five modules, including one that is designated as the “wet core.” The wet core consolidates the mechanical systems and bathroom into a single module to reduce plumbing runs, efficiency losses, and on-site construction time. The other four modules are designed to eliminate interior load bearing walls to allow for maximum flexibility in the reconfiguring of the space over time. The modules are designed to meet the structural challenges of both Florida’s hurricanes and California’s earthquakes. Building Automation System: The house is equipped with an integrated building automation system, allowing the houses environmental systems, lights, security systems, and smoke detectors to be programmed, monitored, and controlled through any mobile or computing device. These systems allow for more precise calibrations of temperature/humidity/lighting to correspond with user needs and preferences, minimizing energy losses with economical night- or day-time setbacks. Solar Dehumidification System: The most significant technological innovation in the Solar Living House is the solar thermal dehumidification system. This system generates hot water through two rooftop-mounted evacuated tube solar thermal collectors. The hot water is used to continually dry a regenerative solid desiccant material, typically white silica gel. The solid desiccant is used to adsorb moisture and humidity from the air without additional mechanical cooling. This strategy allows humidity to be modulated independently of air temperature, providing greater thermal comfort and reducing the opportunity for the growth of mold spores within the house while also reducing the overall energy consumption of the HVAC system. Economic Feasibility: The team set aggressive goals for affordability, targeting a construction cost of $138,710. An independent professional cost estimator determined the overall project costs, as designed, would be $333,799, or $336.15 per square foot of finished floor area. This is more than 2.4 times the target construction cost. By comparison, the average construction cost for a home in the United States in 2015 was $289,415, or $103.29 per square foot of finished floor area. Following work on the Solar Living House, team leaders incorporated many of its objectives into a net-zero energy home on a site in Gainesville, Florida. This site-built home avoided many of the constraints and complications of modular construction necessitated by the Solar Decathlon, allowing it to be built for a much more modest budget. This two-bedroom two bath 1,800 square foot home was constructed for $135.39 per square foot, including active photovoltaic solar systems, careful attention to continuous air barriers, increased insulation levels, and permanent site constructions. This project suggest that high-performance buildings can be realized for more modest budgets. Public Benefits: Work on the Solar Living House and Solar Decathlon 2015 offered our student team unparalleled learning opportunities. Because of the duration of the project, a number of students participated at different points in their education, from first year undergraduates all the way through to advanced graduate students. The opportunity for collaboration with students and faculty from the National University of Singapore was also extraordinary, allowing for a sharing of technical knowledge and cultural exchange. The wider public has benefited from this work as its findings have been shared through public presentations and publications. It serves as a useful stepping stone along the path towards affordable, high-performance buildings.
Conventional wisdom surrounding space heating has told us a couple of things consistently for several years now: size the mechanical systems to the heating loads and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. The implication of this is that, for setback to be successfully implemented, the heating system must be oversized. This issue is exacerbated further when an outdoor reset control is used with a condensing boiler, because not only is the system matched to the load at design, the outdoor reset control matches the output to the load under varying outdoor temperatures. Under these circumstances, the home may never recover from setback. Special controls to bypass the outdoor reset sensor are then needed. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. Determining the appropriateness of setback for a particular project is the first step. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step by step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.
Conventional wisdom surrounding space heating has told us a couple of things consistently for several years now: size the mechanical systems to the heating loads and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. The implication of this is that, for setback to be successfully implemented, the heating system must be oversized. This issue is exacerbated further when an outdoor reset control is used with a condensing boiler, because not only is the system matched to the load at design, the outdoor reset control matches the output to the load under varying outdoor temperatures. Under these circumstances, the home may never recover from setback. Special controls to bypass the outdoor reset sensor are then needed. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. Determining the appropriateness of setback for a particular project is the first step. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step by step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.
The ARIES Collaborative, a U.S. Department of Energy Building America research team, partnered with NeighborWorks America affiliate Homeowners' Rehab Inc. (HRI) of Cambridge, Massachusetts, to study improvements to the central hydronic heating system in one of the nonprofit's housing developments. The heating controls in the three-building, 42-unit Columbia Cambridge Alliance for Spanish Tenants housing development were upgraded. Fuel use in the development was excessive compared to similar properties. A poorly insulated thermal envelope contributed to high energy bills, but adding wall insulation was not cost-effective or practical. The more cost-effective option was improving heating system efficiency, which faced several obstacles, including inflexible boiler controls and failed thermostatic radiator valves. Boiler controls were replaced with systems that offer temperature setbacks and one that controls heat based on apartment temperature in addition to outdoor temperature. Utility bill analysis shows that post-retrofit weather-normalized heating energy use was reduced by 10%-31% (average of 19%). Indoor temperature cutoff reduced boiler runtime (and therefore heating fuel consumption) by 28% in the one building in which it was implemented. Nearly all savings were obtained during night which had a lower indoor temperature cut off (68°F) than day (73° F). This implies that the outdoor reset curve was appropriately adjusted for this building for daytime operation. Nighttime setback of heating system supply water temperature had no discernable impact on boiler runtime or gas bills.
The ARIES Collaborative, a U.S. Department of Energy Building America research team, partnered with NeighborWorks America affiliate Homeowners' Rehab Inc. (HRI) of Cambridge, Massachusetts, to study improvements to the central hydronic heating system in one of the nonprofit's housing developments. The heating controls in the three-building, 42-unit Columbia Cambridge Alliance for Spanish Tenants housing development were upgraded. Fuel use in the development was excessive compared to similar properties. A poorly insulated thermal envelope contributed to high energy bills, but adding wall insulation was not cost-effective or practical. The more cost-effective option was improving heating system efficiency. Efficient operation of the heating system faced several obstacles, including inflexible boiler controls and failed thermostatic radiator valves. Boiler controls were replaced with systems that offer temperature setbacks and one that controls heat based on apartment temperature in addition to outdoor temperature. Utility bill analysis shows that post-retrofit weather-normalized heating energy use was reduced by 10%-31% (average of 19%). Indoor temperature cutoff reduced boiler runtime (and therefore heating fuel consumption) by 28% in the one building in which it was implemented. Nearly all savings were obtained during night which had a lower indoor temperature cut off (68 degrees F) than day (73 degrees F). This implies that the outdoor reset curve was appropriately adjusted for this building for daytime operation. Nighttime setback of heating system supply water temperature had no discernable impact on boiler runtime or gas bills.
The ARIES Collaborative, a U.S. Department of Energy Building America research team, partnered with NeighborWorks America affiliate Homeowners' Rehab Inc. (HRI) of Cambridge, Massachusetts, to study improvements to the central hydronic heating system in one of the nonprofit's housing developments. The heating controls in the three-building, 42-unit Columbia Cambridge Alliance for Spanish Tenants housing development were upgraded. Fuel use in the development was excessive compared to similar properties. A poorly insulated thermal envelope contributed to high energy bills, but adding wall insulation was not cost-effective or practical. The more cost-effective option was improving heating system efficiency. Efficient operation of the heating system faced several obstacles, including inflexible boiler controls and failed thermostatic radiator valves. Boiler controls were replaced with systems that offer temperature setbacks and one that controls heat based on apartment temperature in addition to outdoor temperature. Utility bill analysis shows that post-retrofit weather-normalized heating energy use was reduced by 10%-31% (average of 19%). Indoor temperature cutoff reduced boiler runtime (and therefore heating fuel consumption) by 28% in the one building in which it was implemented. Nearly all savings were obtained during night which had a lower indoor temperature cut off (68 degrees F) than day (73 degrees F). This implies that the outdoor reset curve was appropriately adjusted for this building for daytime operation. Nighttime setback of heating system supply water temperature had no discernable impact on boiler runtime or gas bills.