Re-considering the energy efficient retrofitting approach to question cost-optimality and nZEB under COVID-19 measures

The building energy performance has been highly studied in the last decades considering the indoor environmental quality, and sustainability indicators to examine energy-efficient cost-optimal, and nZEB building levels for different building typologies. However, since the start of the COVID-19 pandemic in 2020, the usage and operation of public spaces and buildings have evolved according to COVID-19 measures produced by the authorities. Social distancing measures and HVAC system measures affecting energy performance and indoor environmental quality of the public buildings are consequently necessary for building energy performance studies. Thereby, it is aimed at re-considering an energy-efficient cost-optimal retrofitting approach for a primary school building case, under the COVID-19 measures to recast an energy-efficient cost-optimal level and apply a cost-efficiency criterion to search for the measures adapted nZEB scenarios. COVID-19 measures affecting building energy performance, such as social distancing and IEQ requirements, were analysed. Then, probable ventilation rates were controlled by the infection probability method to satisfy the limit number for infection. Thus, pre-COVID-19 and post-COVID-19 variables regarding occupancy density and HVAC operation were determined for the calculation process. Besides, retrofit scenarios were shaped to improve optic and thermophysical properties of the façade, lighting, and HVAC systems performance. Then, energy, LCC, thermal comfort and IEQ performance of retrofit scenarios were calculated with a calibrated model. Results were evaluated by applying the cost-efficiency criterion to find out nZEB scenarios. It can be stated that distinct LCC and energy use increments occurred in the cost-optimal range and nZEB level.

Compliance with Building Energy Code for the Residential Sector in Egyptian Hot-Arid Climate: Potential Impact, Difficulties, and Further Improvements

Building energy codes are considered to be an effective policy tool for energy reduction worldwide. However, their application and effectiveness are still limited in developing countries. In Egypt, the residential sector is promising for energy savings, as most of the existing residential buildings are aged with low thermal performance and non-conformance with energy codes. This study aims to raise the awareness of promoting the Egyptian residential energy codes among construction parties, especially end-users, by quantifying the environmental impacts, in terms of energy savings and thermal comfort enhancement. Moreover, it attempts achieving a nearly zero energy building by integrating several energy-efficient measures with renewable energy sources. Thus, in this study, a typical residential building in Cairo was chosen for simulation. The simulation results revealed that applying energy code instructions for building envelope, lighting enhancement and increases in cooling set-points, from 24 °C to 25 °C, saved 37.85% of annual electrical energy and resulted in a cooling reduction of 50.53%. Furthermore, the photovoltaic system incorporation succeeded in transforming the building into a nearly zero energy building. Concerning thermal comfort, the application of passive energy-efficient measures significantly influences indoor thermal comfort, with a 30% reduction in discomfort hours during the cooling season, which represents the main concern in hot climate regions.

Thermo-Energy Performance of Lightweight Steel Framed Constructions: A Case Study

The building sector continues to play an essential role in reducing worldwide energy consumption. The reduced consumption is accompanied by stricter regulation for the thermotechnical design of the building envelope. The redefined nearly Zero Energy Building levels that will come into force for each member state will pressure designers to rethink the constructive details so that mandatory levels can be reached, without increasing the construction costs over an optimum level but at the same time reducing greenhouse gas emissions. The paper aims to illustrate the main conclusions obtained in assessing the thermo-energy performance of a steel-framed building representing a holistically designed modular laboratory located in a moderate continental temperate climate, characteristic of the south-eastern part of the Pannonian Depression with some sub-Mediterranean influences. An extensive numerical simulation of the main junctions was performed. The thermal performance was established in terms of the main parameters, the adjusted thermal resistances and global thermal insulation coefficient. Further on, the energy consumption for heating was established, and the associated energy rating was in compliance with the Romanian regulations. A parametric study was done to illustrate the energy performance of the investigated case in the five representative climatic zones from Romania. An important conclusion of the research indicates that an emphasis must be placed on the thermotechnical design of Light Steel Framed solutions against increased thermal bridge areas caused by the steel’s high thermal conductivity for all building components to reach nZEB levels. Nevertheless, the results indicate an exemplary behaviour compared to classical solutions, but at the same time, the need for an iterative redesign so that all thermo-energy performance indicators are achieved.

Performance analysis of a hybrid ventilation system in a near zero energy building.

In this research paper, an analysis is developed on the performance of a hybrid ventilation system that combines Earth-to-Air Heat eXchangers (EAHX), free cooling and evaporative cooling Air Handling Unit Heat eXchanger (AHU-HX), all being controlled by a Building Management System (BMS) in a net Zero Energy Building (nZEB), called LUCIA. LUCIA nZEB is the first safe-building against Covid-19 in the world, certified by the international organisation WOSHIE, and located in Valladolid, Spain. The main aim is to optimize the performance of the three systems in such a way that the Indoor Air Quality (IAQ) levels remain within the allowable limits, while maximizing the use of natural resources and minimizing energy consumption and carbon emissions. The approach to satisfy the heating and cooling demand and IAQ levels through zero emissions energy systems is developed, thus anticipating the zero-energy target, set by the European Union for 2050. Results showed that the installed hybrid ventilation system uses heat exchangers for 70% of the operational time, in order to achieve the set parameters successfully. Also, the analysis made by monitoring data, have shown that the control and optimal operation of the hybrid ventilation system allows high energy recovery values with minimum additional electricity consumption. Significant reduction of carbon emissions and operational costs have been achieved.