Energy Consumption For Domestic Hot Water Research Articles

Assessment of Social Housing Energy and Thermal Performance in Relation to Occupants’ Behaviour and COVID-19 Influence—A Case Study in the Basque Country, Spain

Evidence shows that people have a major impact on building performance. Occupants’ impact is especially important in social housing, where their occupants may present greater vulnerabilities, and their needs are not always considered. This study aims to analyse the socio-demographic influence in social rental housing concerning hygrothermal comfort and energy consumption in a case study located in Vitoria, Spain during the first 4-month period of 2020 and 2021 (during and after COVID-19 lockdown). An innovative data management system is included, where the users and administration can see in real-time the temperature and consumption in the dwellings. A 2-phase method has been applied; phase 1 is associated with outdoor climate conditions, building properties and social profile. Phase 2 determined the results in energy consumption, indoor hygrothermal comfort and occupant energy-use pattern. The results show that the comfort levels and energy consumption vary according to the analysed social profiles, as well as the heating activation periods and domestic hot water system usage. In conclusion, socio-demographic characteristics of social housing households influence the hygrothermal comfort of their dwellings, occupants’ behaviour and heating and domestic hot water energy consumption.

Incorporating novel heat recovery units into an AHU for energy demand reduction-exergy analysis

The building sector is the major energy consumer, accounting for over 40% of global energy demand. Heating and cooling together with domestic hot water energy consumption are estimated to account for 60% of the required energy for buildings’ maintenance and operation. Energy recovery is a suitable technique to tackle high energy consumption in the building. In this study, a new layout of heat recovery units installation (i.e., primary and secondary) is investigated. The main objective of this study is to reduce energy consumption in an air handling unit through the exergy analysis. Owing to adding heat recovery units, cooling and heating coil loads reduced by 7.8% and 43%, which in turn decreased the total required load of AHU by 17.84%. From the viewpoint of the second law and based on the results, incorporating the primary and secondary heat recovery units into the base AHU in hot and dry climate regions led to decrease in the total irreversibility up to 26.29%, while in hot and humid climate this figure is 14.25%. Consequently, the positive effect of using heat recovery units in the hot and dry climate region is superior to the hot and humid one.

The Influence of Energy Renovation on the Change of Indoor Temperature and Energy Use

The aim of the renovation of apartment buildings is to lower the energy consumption of those buildings, mainly the heating energy consumption. There are few analyses regarding those other energy consumptions which are also related to the primary energy need for calculating the energy efficiency class, including the primary energy need of calculated heating, domestic hot water (DHW), and household electricity. Indoor temperature is directly connected with heating energy consumption, but it is not known yet how much it will change after renovation. One of the research issues relates to the change of electricity and DHW usage after renovation and to the question of whether this change is related to the users’ behavior or to changes to technical solutions. Thirty-five renovated apartment buildings have been analyzed in this study, where the data of indoor temperature, airflow, and energy consumption for DHW with and without circulation and electricity use in apartments and common rooms has been measured. During research, it turned out that the usage of DHW without circulation and the usage of household electricity do not change after renovation. Yet there is a major increase in indoor temperature and DHW energy use in buildings that did not have circulation before the renovation. In addition, a small increase in the use of electricity in common areas was discovered. This study will offer changes in calculations for the energy efficiency number.

In-building waste water heat recovery: An urban-scale method for the characterisation of water streams and the assessment of energy savings and costs

Residential domestic hot water energy consumption represented 16% of the EU household heating demand in 2013. With the improvement of the building insulation envelope, domestic hot water contribution to energy consumption is expected to increase significantly, with values between 20% and 32% in single family buildings, and between 35% to almost 50% in multifamily buildings. This energy, currently lost to the environment, can be recovered by waste water heat recovery systems inside buildings (in-building solutions). While most publications in this field focus on shower heat recovery and on waste water as heat source for heat pumps, the detailed impact of waste water heat recovery at a city scale by aggregating building data has not been addressed yet. Furthermore, waste water heat recovery potential and relevance was not yet quantified as a function of the specific inhabitant and household numbers, end-use occurrence, and building type and age.A method to quantify the building-specific energy cost and energy saving potentials, based on pinch analysis, at the urban scale of in-building waste water heat recovery systems is therefore proposed. A complementary method to spatially allocate and characterise grey water streams as to thermal load and temperature levels in function of the building specificities is also developed.These methods are applied in two case studies, first as retrofitting solution in a city in Luxembourg and, second, as optimisation measure for high efficiency residential buildings. Grey water heat recovery would reduce the residential fuel consumption of the city by 6.3%. An integrated approach combining grey water heat recovery for hot water preheating and a heat pump yields up to 28% and 41% electricity savings for passive single family houses and multifamily buildings, respectively.With the detailed characterisation of various grey water streams as a function of inhabitant number and end-use occurrence, the quantification of the energy savings and costs through heat recovery is improved. The outcomes of urban energy and cost assessments concerning grey water heat recovery are more specific, as the results at building level are aggregated to the considered geographical scope. The proposed method therefore complements current urban energy and cost assessments with the detailed integration of in-building grey water heat recovery systems.

Investigations of Nearly (net) Zero Energy Residential Buildings in Beijing

Zero energy buildings have attracted more and more attention recently in the world. This research work studied the feasibility of a 12-storey plank-type building achieving zero energy. The study used Software TRNbuild to establish a 12-story residential building, as a reference building, based on DB11/891—2012(Design Standard for Energy Efficiency of Residential Buildings of Beijing). On the one hand, the study does passive building design, including high performance envelope, air-tightness and fresh air heat recovery efficiency, to reduce heating and cooling load. On the other hand, TRNSYS was used to simulate building energy system, such as solar domestic hot water systems (SDHW), unitary air-source heat pump for space heating and cooling, and renewable electricity system-PV. Annual energy consumption of reference buildings (central heating system for heating, ASHP for cooling) is 30.33 kwh/(m2•a) . By contrast, that of NZEBs(ASHP for heating and cooling)is 11.1 kwh/(m2•a), declining by more than half. PV array production on the roof can meets its energy demand. If domestic hot water energy consumption is also included, PV array production on the roof can offer 95.8% of total electricity demand. In general, it's entirely feasible for residential buildings in Beijing to achieve nearly zero energy.

Life Cycle Impact Assessment of a Solar Assisted Heat Pump for Domestic Hot Water Production and Space Heating

Solar heat pumps (SHP) are a class of heating systems combining solar thermal technology with heat pumps. In this article the life cycle impact assessment (LCIA) of a SHP system used to produce domestic hot water (DHW) and space heating (SH) for single family dwellings is presented. This study intends to evaluate the environmental impacts of the energy and material used in a serial SHP installation and identify areas for improvement by applying a “cradle-to-grave” approach when analysing the system. This includes the installation materials both in their manufacturing and disposal phases as well as the energy consumption for DHW and SH throughout a service life of 20 years. In addition, it provides a comparison against two other residential heating systems operating with the same life expectancy. In this LCIA, two environmental related indicators are used, one associated with depletion of non-renewable energy resources (CEDNRE) and the other with climate change (GWP). The impact of the type of electricity used was also investigated by defining, in addition to the European supply mix, an alternative supply mix with electricity deriving from renewable sources. This study shows that SHP have lower environmental impacts than systems operating on electricity only. Installations with large solar collector surfaces are also seen to lead to lower energy consumption related impacts. If the electricity used by these systems derives from renewable sources, the environmental performance improves. However, under these conditions, the SHP impact (material and energy consumption) related to climate change will be of the same order as that of the electric system due to a higher contribution of the infrastructure content of these systems.

Heat Consumption Assessment of the Domestic Hot Water Systems in the Apartment Buildings

This study presents the analysis of energy consumption for domestic hot water in apartment buildings in Riga, Latvia. The aggregate data contains information about 39 apartment buildings, including heat energy consumption and domestic hot water (DHW) consumption. The analysis is focused on the heat energy consumption and seasonal characteristics in the DHW system. The analysis characterizes the DHW consumption, energy consumption for DHW and energy losses in the DHW systems in apartment buildings. The energy consumption of DHW needs of households and some other building sectors constitutes a significant part of the building's energy balance. The building energy efficiency improvement measures reduce the heating energy required proportion and logically increase the share of energy consumption for DHW needs. It is likely that the production and distribution of DHW in buildings will constitute a dominant share of both the present, and in particular, the future energy design requirements of buildings. (1) Previously studies carried out in various European countries (2), (3), (4), China (5), (6), Japan (7), (8), (9), USA (10), (11), Canada (12) points the many differences in DHW consumption as well as the tendency to change over time due to a global increase of energy prices, changes in technologies, introducing of individual metering, as well as wide variety of other factors that may appear on local or regional level. Measurements in Denmark documented not only a relatively high energy consumption for DHW in apartment buildings, but also recorded surprisingly large heat losses from the DHW circulation lines (13), (14). Recent investigation of 24 buildings in Danmark shows that most of the energy demand for DHW is lost in the circulation system. The efficiency was 0.30-0.77 (heat loss 23-70%) in apartment buildings and efficiency 0.11- 0.46 (heat loss 54-89%) in office buildings. (1) The Energy Performance of Buildings Directive (EPBD) (15) in the version of 2010, the so-called recast EPBD, demands in annex I 'Common general framework for the calculation of energy performance of buildings (referred to in Article 3)' that '(1) the energy performance of a building shall be determined on the basis of the calculated or actual annual energy that is consumed in order to meet the different needs associated with its typical use and shall reflect the heating energy needs and cooling energy needs (energy needed to avoid overheating) to

Occupant related household energy consumption in Canada: Estimation using a bottom-up neural-network technique

A national model of residential energy consumption requires consideration of the following end-uses: space heating, space cooling, appliances and lighting (AL), and domestic hot water (DHW). The space heating and space cooling end-use energy consumption is strongly affected by the climatic conditions and the house thermal envelope. In contrast, both AL and DHW energy consumption are primarily a function of occupant behaviour, appliance ownership, demographic conditions, and occupancy rate. Because of these characteristics, a bottom-up statistical model is a candidate for estimating AL and DHW energy consumption. This article presents the detailed methodology and results of the application of a previously developed set of neural network models, as the statistical method of the Canadian Hybrid Residential End-Use Energy and Greenhouse Gas Emissions Model (CHREM). The CHREM estimates the national AL and DHW secondary energy consumption of Canadian single-detached and double/row houses to be 248 PJ and 201 PJ, respectively. The energy consumption values translate to per household values of 27.8 GJ and 22.5 GJ, and per capita values of 9.0 GJ and 7.3 GJ, respectively.

Analysis of domestic hot water energy consumption in large buildings under standard conditions in Senegal

This paper presents an investigation of the energy consumption due to domestic hot water (DHW) production in large buildings. We have studied three types of reference buildings: one office, one residence and a 3-star hotel located in Senegal. The DOE2.1E (the building energy program of the Department of Energy Version 2.1E) has been used. One of its main advantage is that it allows to take into account both energy end use categories and a great number of parameters of the building energy performance. Four climatic regions have been identified and their equivalent “standard” conditions are all defined. Those conditions are the same as the current design and operating conditions of each type of building. The DHW energy consumption is calculated and compared with the total energy generated by all end uses (lighting, cooling/ventilation, DHW, and other equipment). Before we carry out wide and systematic simulations of the three buildings energy performance, we pay special attention to check and validate the DHW part of the DOE2.1E model. There was an agreement between the recorded monthly DHW energy load on the one hand, and on the other the computed results. We end up finding results that could open new perspectives for building a strategic methodology to provide guidelines for DHW energy saving measures in large buildings in West Africa. Furthermore, it is expected that energy researchers concerned about energy and environmental efficiency would consider this study for promoting CO 2 emission reduction in relation with DHW production in large buildings.