A deep energy retrofit (DER) is an energy conservation project in an existing building that leads to an overall improvement in building performance. While there is no exact definition for a deep energy retrofit, it can be characterized as a whole-building analysis and construction process that aims to reduce on-site energy use by 50% or more using existing technologies, materials and construction practices.Less, Brennan, et al. "Deep Energy Retrofit x 10." Home Energy, vol. 29, no. 3, 2012, p. 38."The Retrofit Depot", Rocky Mountain Institute, 2018, https://www.rmi.org/our-work/buildings/deep-retrofit-tools-resources/deep-retrofit-case-studies/. Accessed Dec 2018. Reductions are calculated against baseline energy use using data from utility bills. Such a retrofit reaps multifold (energy and non-energy) benefits beyond energy cost savings, unlike conventional energy retrofit. It may also involve remodeling the building to achieve a harmony in energy, indoor air quality, durability, and thermal comfort.Cluett, Rachel, and Jennifer Amann. "Residential Deep Energy Retrofits." American Council for an Energy-Efficient Economy (ACEEE), American Council for an Energy-Efficient Economy, 11 Mar. 2014, aceee.org/research-report/a1401. An integrated project delivery method is recommended for a deep energy retrofit project.Less, Brennan, and Iain Walker. "Deep Energy Retrofit Guidance for the Building America Solutions Center." Contract No. DE-AC02-05CH11231. California: United States Government, 2015. An over-time approach in a deep energy retrofitting project provides a solution to the large upfront costs problem in all-at-once execution of the project.
A deep energy retrofit is a whole-building analysis and construction process that achieves much larger energy savings than conventional energy retrofits. Deep energy retrofits can be applied to both residential and non-residential ("commercial") buildings. A deep energy retrofit typically results in energy savings of 30 percent or more, perhaps spread over several years, and may significantly improve the building value.
Climate Change
82% of final energy consumption in buildings was supplied by fossil fuels in 2015. The energy-related emissions account for the environmental impact due to a building. The Global Status Report 2017 prepared by the International Energy Agency (IEA) for the Global Alliance for Buildings and Construction (GABC) highlights the significance of the buildings and construction sector in global energy consumption and related emissions again."Global Status Report 2017", World Green Building Council, 2016-2018, https://www.worldgbc.org/news-media/global-status-report-2017. Accessed Dec 2018. Deep energy retrofits will assist in achieving the global climate goals laid down in the Paris Agreement.
Deep energy retrofits vs. Conventional energy retrofits Conventional energy retrofits focus on isolated system upgrades (i.e. lighting and (HVAC) Heating, ventilation, and air conditioning equipment). While these retrofits are generally simple, fast and comparatively inexpensive, deep energy retrofits, while expensive, replace systems to be more energy efficient.
Deep energy retrofits require a systems-thinking approach compared to the traditional approach followed for a conventional retrofit – home weatherization or typical home performance upgrade. Systems thinking evaluates the interactions between the different isolated components in the building. For example, Home Performance with ENERGY STAR offers a comprehensive, whole-house approach to improving a home's energy efficiency, comfort and safety while helping to reduce the energy costs by up to 20%.Home Performance with ENERGY STAR, Maryland Energy Administration, https://bgesmartenergy.com/residential/home-performance-energy-star. In addition to the efficiency measures taken for a building, a deep energy retrofit requires occupants' proactive role in energy conservation. This approach usually takes into account all the energy uses in the home, as well as the activities of the occupants.
Deep energy retrofits achieve greater energy efficiency by taking a whole-building approach, addressing many systems at once. It is usually more economical and convenient to take this approach on buildings with overall poor efficiency performance, with multiple systems nearing the end of useful life, and perhaps other reasons.
Occupant behavior The overall success of the deep energy retrofit project can depend upon the inclusion of occupants in all the phases of the project. The phases include – project recruitment, project planning and use. Occupant behavior requires the project to focus on building owners' needs and wants as much as the technical specifications. This ascertains actual performance, cost-effectiveness, willingness to progress from a design to an actual implementation, and occupant satisfaction. Also, evidence suggests that building simulation models can become more accurate for a given structure when actual operational information, such as thermostat set-points, appliance usage, etc. are included.Ingle, A., Moezzi, M., Lutzenhiser, L., Hathaway, Z., Lutzenhiser, S., Van Clock, J., ... Diamond, R. (2012). Behavioral Perspectives on Home Energy Audits: The Role of Auditors, Labels, Reports, and Audit Tools on Homeowner Decision-Makingq (No. LBNL-5712E). Berkeley, CA: Lawrence Berkeley National Lab.
In Europe, for funding for retrofitting, there are unique European Union bank initiatives that offer funds or help, including the Joint European Support for Sustainable Investment in City Areas initiative and the European Local Energy Assistance (ELENA) project.
Over-time Retrofit Over-time retrofit is the implementation of a retrofit project which is planned in a step-by-step manner at intervals of time within a stipulated duration. Such an approach is usually sought for deep energy retrofits over an all-at-once approach to reduce the burden of large upfront costs. Thus, an over-time retrofit can be a more viable option when there are capital constraints. Research in the United Kingdom has demonstrated that retrofits carried out over-time can achieve levels of home performance equal to those achieved by all-at-once DERsFawcett, T., Killip, G., & Janda, K. B. (2014). Innovative Practices in Low Carbon Retrofit: Time, Scale and Business Models. In Paradigm Shift: From Energy Efficiency to Energy Reduction Through Social Change. Oxford, England. Retrieved from http://behaveconference.com/wp-content/uploads/2014/08/F_Tina_Fawcett_University_of_Oxford.pdf and select projects have been successful in the United States.Less, B., & Walker, I. (2014). A Meta-Analysis of Single-Family Deep Energy Retrofit Performance in the U.S. (No. LBNL-6601E). Berkeley, CA: Lawrence Berkeley National Laboratory. Retrieved from http://eetd.lbl.gov/sites/all/files/a_meta-analysis_0.pdf The pros and cons of an over-time retrofit are compared as follows: +Over-time RetrofitPotential benefitsPotential downsidesLess perceived disruption, because it is spread out over-time.More numerous small disruptions.More likely that occupants can continue to inhabit their home continuously,
without any need for alternative accommodations.Difficult to finance traditionally.Costs are spread over-time, allowing owners to build up savings between phases.Costs may be higher, due to repeated fees and fixed costs, such as
permitting, inspection and construction labor.Introduce occupants to the benefits of energy upgrades, thus feeding their desire for further improvements and refinements.Possible need to reinvest in measures that are inadequately addressed, due to a lack of careful and detailed planning.More aligned with making incremental deep green improvements, as maintenance and equipment replacement require.Lower aggregate energy savings and reduction in environmental footprint.Over-time process can inform occupants of the effects of their behaviors, and the potential for behavior modification to reduce energy use and project costs (through use of human effort rather than technology to achieve savings).Difficult for occupants to delay the gratification of investing in glamorous efficiency measures (such as solar PV or windows), by first investing in the invisibles (insulation and airsealing).
For example, an overtime retrofit project could be able to stipulate the occupants' need but could perform sub-optimal technically. It could also prove to be costlier. There is a lack of tools to execute over-time projects efficiently.
Strategies to increase success Detailed planning must be inculcated from the beginning. It is recommended to include post-occupancy evaluation at each stage of implementation to deal with modifications required in future stages. Home performance should be tracked at each stage using utility bills or feedback devices. This helps in achieving the set-target for energy consumption. It must be kept in mind to implement building envelope and passive design elements before making major heating, ventilation, and air conditioning (HVAC) and technology investments. This will help to reduce the load parameters for heating, ventilation, and air conditioning (HVAC) design. The technology investments should also come later to have an innovation advantage. Over-time retrofits can be guided by these strategies to be successful.
Design and Construction Process
Deep energy retrofit projects have different phases governing them – pre-panning, project planning, construction, and test out. For the design and construction process, a set of defined project needs, opportunities, goals and objectives should be created. This determines the overall project. Walker et al. provide design and construction process guidance which can be followed flexibly in deep energy retrofit projects in residential homes. +Design and Construction Phases1Pre-Planning Phase1.1Establish and clarify the project needs, opportunities, goals and objectives1.2Establish a performance baseline1.2.1Perform home inspection and energy audit1.2.2Identify Healthy Homes health and safety issues1.2.3Establish energy baseline using utility bill analysis1.3Develop project goals and performance metrics1.3.1Establish an annual performance target or energy reduction goal1.3.2Establish metrics to be used in assessing progress towards project goals1.3.3Establish non-energy goals of the project2Project Planning Phase2.1The design team2.1.1Assemble qualified and trusted team2.1.2Planning approaches2.1.2.1Plan all aspects of the project as if it were new construction2.1.2.2Systems integrated approaches2.1.2.3Design to the energy reduction goal or target2.1.2.4An integrated project delivery method2.1.2.5Use energy models3Construction Phase3.1Plan product procurement for a DER as for any remodel3.2Be prepared for unexpected issues to arise3.3Provide quality assurance wherever possible4Test Out4.1Verify installation and performance of retrofit measures4.2Commission all building systems5Post-Occupancy Evaluation5.1Provide post-occupancy performance feedback to occupants5.2Encourage occupants to make acceptable behavioral adjustments5.3Guide occupants using short-term usage targets
Energy efficiency measures Cluett and Amann (2014) found the most commonly implemented efficiency measures in the US for residential buildings. They are broadly listed as follows.
Building shell improvements Insulation improvements, usually to the foundation walls/slabs, above grade walls, floors, roof, and attic surfaces that make up the thermal envelope Attention to air sealing, particularly in areas that are harder to address without being paired with improvements to the insulation shell
Upgrades to heating, cooling, and hot water systems Upgrade to non-atmospheric vented combustion units that either vent directly outside or are electric only Upgrade to units that are correctly sized for the heating and cooling load demands of an altered building