Assessing the building envelope performance during occupancy

Cost-optimal energy performance calculations of a new nZEB hotel building using dynamic simulations and optimization algorithms

One way to achieve carbon neutrality is by improving the energy performance of existing buildings, which requires accurate measurements. In particular, accurate measurement of heat loss coefficient (HLC) is critical because a building envelope is an important parameter of the energy performance analysis. The international standard for measuring HLC is heat flow meter (HFM) method in ISO 9869-1, which can be used to obtain the HLC at representative points on the building envelope. However, this approach does not account for the HLC of thermal bridges, which means that adding up the HLCs obtained for individual elements of the building envelope underestimates the total HLC of the building. In this study, the in situ thermal bridge measurement (TBM) method, which combines the HFM method and the coheating test, was proposed. In situ TBM can quantitatively measure the HLCs of multiple thermal bridges within an existing building envelope without requiring information on the internal structure or material properties. Measurement tests in an experimental chamber demonstrated that the in situ TBM method can be used to quantify the HLC of thermal bridges, which are missed when the HFM method is used alone.

It is widely accepted that the concentration of people living in high-density city centers offers greater operational energy efficiency and lower greenhouse gas emissions than lower-density expanded suburbs. The prevailing assumption is that lower-density suburbs are dominated by larger low-rise buildings that have higher building energy use requirements and greater per-person automobile travel requirements than high-density city centers dominated by medium- and high-rise buildings located in close proximity to a variety of public transit systems. However, very few studies to date have utilized empirical data at an individual household scale to evaluate differences in the operational energy (OE) footprints for both building and transportation energy end-uses between high-rise urban and low-rise suburban households. Therefore, this work collects empirical data on building and transportation OE consumption by individuals and households living in two economically similar groups: existing high-rise residential buildings in downtown Chicago, IL, USA and existing low-rise residential buildings in suburban Oak Park, IL, USA. Data were collected from over 500 households via an online survey. We considered the following components of residential living: (1) building OE (BOE), which includes electricity and/or natural gas use for all building energy end-uses; and (2) transportation OE (TOE), which includes the OE for multiple modes of transportation (i.e., automobile, bus, subway, regional train, etc.) based on average travel behavior in each location, as well as the OE for supporting transportation infrastructure. We estimate that downtown high-rise living in this sample of residences in Chicago, IL accounts for approximately 427 GJ of primary OE per household per year, on average, which was 14% lower than the average for suburban low-rise living in the Oak Park, IL homes (499 GJ per household per year). However, on a per-person basis, downtown high-rise living accounts for approximately 246 GJ of primary OE per person per year, which was approximately 61% higher than suburban low-rise living (153 GJ per person per year). In both building types, building OE was the single largest contributor to total OE use. This study accurately captured the energy requirements associated with realistic behaviors and lifestyles of occupants of both low-rise suburban and high-rise urban households, and found that building OE dominates the total OE, which suggests that efforts to reduce building OE should be given high priority in building design and management as well as urban planning.

The impact of energy performance certificates: A survey of German home owners

PurposeThe aim of the research is to determine the influence of photovoltaic (PV) installation and the share of façade glazing on the energy profile of nursery buildings in the Baltic Sea region, as well as defining the most favorable configuration in terms of energy efficiency.Design/methodology/approachThe article provides comparative calculations of energy performance indicators (Ep, Ed, Eu) and CO2 emissions (mCO2) made for the defined model of the nursery. It includes calculations concerning energy performance of the building, depending on its PV power (0–60 kWp), PV efficiency (100 and 85%) and façade glazing ratio (GR = 25%, 50% and 75%).FindingsThe results of the research indicate that an increase in the PV power exerts proportional impact on the reduction of the Ep and Ed indicators, as well as on the CO2 emissions. Only low GR values (25%) reduce the Eu indicator significantly. Decrease in high range of GR values (over 50%) does not provide proportional effects. In the variant: 60 kWp (100% efficiency) with GR = 25%, the biggest share (99.5%) of RES was obtained. This proves that the concept of energy independent nursery buildings is feasible and reasonable in the examined location.Practical implicationsDesigning buildings towards environmental neutrality requires laborious pre-design conceptual work before developing the right solutions. The set of results of the relationship between the variables of the building's envelope, energy performance indicators and the required involvement of active RES installations to achieve high energy performance of a building presented in the article is valuable. It allows for a preliminary decision of the direction of the design solutions selection in the design process of public utility buildings, such as nurseries. Thus, it may significantly shorten the pre-design analysis process for the location of the southern part of the Baltic Sea region.Originality/valueThe novelty of the paper relies on examining the dependences between PV power and façade glazing ratio in terms of their influence on energy profile of nursery buildings.

Characterization of building energy performance indicators such as the Heat Loss Coefficient (HLC) based on in-situ measurement data calls for thorough building physical insight, a well -designed measurement set-up to collect sufficient, qualitative data and adequate data analysis methods. On-board monitoring may be an alternative for dedicated experiments to perform the data collection task. This paper analyses the sensitivity of the end-result of the characterization, the H LC estimate, to flaws in the monitoring data set. More specifically, the impact of not installing submeters to disentangle the gas consumption for space heating and the production of domestic hot water is evaluated. Hereto, multiple gas decomposition methods are applied on a case study monitoring data set, after which the HLC is assessed. The results show deviations up to 33% for the mea n estimate and non-overlapping 95% confidence intervals.

These data support the research article “Improving energy savings from a residential retrofit policy: a new model to inform better retrofit decisions” – (Mac Uidhir et al., 2019) [1]. This article presents 3 data sources which are utilised in conjunction with a detailed energy system model of the residential sector to explore policy pathways for residential retrofitting. Data is collected from the Central Statistics Office (CSO) and the Sustainable Energy Authority of Ireland (SEAI). The first SEAI dataset is compiled for Ireland in compliance with the EU Energy Performance of Buildings Directive (EPBD) [2]. Data is collected using the Dwelling Energy Assessment Procedure (DEAP) [3]. DEAP is used to produce energy performance certificates known as Building Energy Ratings (BER). A BER indicates a buildings energy performance across a 15-point energy efficiency scale, rated alphabetically from A1 to G, in units of kWh/m2 year. A BER is required for new buildings and the rent or sale of existing dwellings – therefore the database has consistently grown in size since its inception in 2006. The BER database contains 735,906 records of individual dwellings. The database includes detailed building fabric information across a range of different building types, year of construction, Main/Secondary space/water heating fuels, heating system efficiency, ventilation method and structure type (Insulated concrete form, Masonry, Timber or Steel Frame). The second SEAI dataset (PWBER) contains aggregated pre and post BER information for a sample of 112,007 dwellings retrofitted during the period 2010–2015; this database contains mean energy efficiency improvement (kWh/m2 year) for a range of retrofit combinations as they apply to nine distinct building archetypes. The third CSO dataset is compiled from census data, representing the frequency of building types by year of construction.

A new methodology for cost-optimal analysis by means of the multi-objective optimization of building energy performance

Assessing Lighting Energy Saving Potential from Daylight Harvesting in Office Buildings Based on Code Compliance & Simulation Techniques: A Comparison

Improving energy efficiency and increasing the level of intelligence are two main factors determining the current development trends for new and modernized buildings. They are especially important in the perspective of development of prosumer installations and local microgrids. A key tool to achieve these goals is a well-designed and implemented Building Automation and Control System (BACS). This paper presents a new hybrid approach to the design and technical organization of BACS based on the provisions of the EN 15232 standard and the guidelines of the Smart Readiness Indicator (SRI) defined in the Energy Performance of Buildings Directive 2018 (EPBD 2018). The main assumptions of this hybrid approach along with examples of functional BACS designs for small prosumer installations organized according to them are provided. Potential impact on building energy performance is discussed as well. Finally, a SWOT analysis of the possibility of merging the EN 15232 standard guidelines and the SRI assessment methodology to develop uniform technical guidelines for the BACS functions design and evaluation of their impact on the buildings’ energy efficiency are discussed.

In this chapter, the development of a computer tool for the determination of nearly zero energy buildings (nZEB) metrics upgraded with life cycle assessment (LCA) and life cycle cost (LCC) indicators is presented, following the requirements of the Energy Performance of Buildings Directive (EPBD). The computer tool was developed for the assessment of new and renovated buildings to support the holistic decision-making process. The tool itself consists of two modules: the building description module (BDU), based on the national certification tool of buildings’ energy performance, and the LCA tool (Etool). BDU enables the assessment of energy needs, final energy demand, and primary energy needs. According to the EPBD, supporting standards was upgraded with the life cycle inventory database. The database includes data on predefined building materials, envelope components, heat generators, and energy carriers and is used by Etool with which mid-point and end-point life cycle impact assessment can be done by taking into account impact groups and damage factors from IMPACT2002+ and ReCiPe methods. The LCC assessment module, which is also part of Etool, was developed according to Commission Delegated Regulation No. 244/212. The use of computer tools is demonstrated through the case studies.

The scope of the Energy Performance of Buildings Directive (2002/91/EC and 2010/31/EC) is the reduction of energy use in buildings in the EU. A principal aspect of the directive is the calculation of an energy certificate for new and existing property. This certificate is intended to provide a measure of the energy efficiency of a building. This research investigates the accuracy of the current methodology used to establish the energy performance of buildings in Malta, where the load profile for energy demand is significantly different to Northern and Central Europe, with a much lower heating load in winter, and a requirement for cooling in summer. The analysis is carried out by a comparison between the official calculation procedure, the use of a dynamic hourly analysis program, and the use of metered data for a case study.

Estimation of building energy performance for local energy policy at urban scale

Undoubtedly Europe is facing challenges in the field of economy and energy which are definitely strongly related. The high energy prices, the growing energy demand, the security risks, the climate change parameter, the need for introducing energy upgrade and low carbon measures, form the basic parameters for the energy and environmental policy. Therefore, a list of European Union (EU) directives, standards were adopted specifying the provisions for the energy upgrade as well as energy certification of buildings. The 2010 Energy Performance of Buildings Directive (EPBD), the 2012 Energy Efficiency Directive and the 2018 recast constitute at present the main European legislations concerning the reduction of the energy consumption of the building sector. The nearly Zero or Zero Energy Building (nZEB) was introduced setting the renewable energy sources use a crucial parameter for the upgrade of energy efficiency in buildings. In correspondence to energy, CO2 emission reduction is another quantified goal set in the EU policy. Targeting to compare efficiently the legislation framework of the two countries the crucial parameters concerning the energy performance of residential and commercials buildings were chosen. These parameters are the U values, the energy rating classes, the lighting contribution, as well as the thermal bridges evaluation. Moreover, for Greece was chosen climate zone A, for example, Crete, where the climate is practically identical to the Cypriot conditions aiming to comment successfully on the framework followed by two countries and how the legislation can be successfully implemented.

The energy performance of buildings directive (EPBD) (91/2002/EU) opened the way for member states of European Union to create and apply a holistic approach on buildings’ energy performance. Taking into consideration the reduced ratio of new buildings, energy refurbishment of existing building stock appears as a nodal point. In particular, buildings in Greece accounts approximately 4 million, while 70% has been constructed before the implementation of the first Thermal Insulation Regulation (TIR), thus they do not have any insulation. So, there is an extremely high potential for energy conservation in Greek building stock. Therefore, an extensive field study was carried out in northern area of Greece in Thessaloniki, through a detailed questionnaire. The purpose of the research is to create an integrated thermal insulation scheme in order to succeed the highest mitigation of energy losses through building envelope. Retrofitting insulation solutions were evaluated and applied through various simulation scenarios with different levels of insulation thickness.