Several studies on indoor air quality (IAQ) and sick building syndromes have been completed over the last decade, especially in cold countries. Efforts to make homes airtight to improve energy efficiency have created buildings with low ventilation rates, resulting in the build-up of indoor pollutants to harmful levels that would be otherwise unacceptable outdoors. This paper analyzed the infiltration rates, indoor temperatures, and variations in CO2, 2.5 μm particulate matter (PM2.5), and total volatile organic compound (TVOC) concentrations over the fall of 2021 in several homes in New England, USA. A relationship between outdoor and indoor conditions and ventilation strategies has been set using the results from blower door tests and actual indoor air quality data. Although all case studies lacked mechanical ventilation devices, such as those required by ASHRAE Standard 62.2, natural ventilation and air leakage have been enough to keep VOCs and PM2.5 concentration levels at acceptable values most of the studied time. However, results revealed that 25% of a specific timeframe, the occupants have been exposed to concentration levels of CO2 above 1000 parts per million (ppm), which are considered potentially hazardous conditions.

High initial costs hinder innovative technologies for building envelopes. Life Cycle Assessment (LCA) should consider energy savings to show relevant economic benefits and potential to reduce energy consumption and CO2 emissions. Life Cycle Cost (LCC) and Life Cycle Energy (LCE) should focus on investment, operation, maintenance, dismantling, disposal, and/or recycling for the building. This study compares the LCC and LCE analysis of Water Flow Glazing (WFG) envelopes with traditional double and triple glazing facades. The assessment considers initial, operational, and disposal costs and energy consumption as well as different energy systems for heating and cooling. Real prototypes have been built in two different locations to record real-world data of yearly operational energy. WFG systems consistently showed a higher initial investment than traditional glazing. The final Life Cycle Cost analysis demonstrates that WFG systems are better over the operation phase only when it is compared with a traditional double-glazing. However, a Life Cycle Energy assessment over 50 years concluded that energy savings between 36% and 66% and CO2 emissions reduction between 30% and 70% could be achieved.

The new paradigm of Net Zero Energy buildings is a challenge for architects and engineers, especially in buildings with large glazing areas. Water Flow Glazing (WFG) is a dynamic façade technology shown to reduce heating and cooling loads for buildings significantly. Photovoltaic panels placed on building roofs can generate enough electricity from solar energy without generating greenhouse gases in operation or taking up other building footprints. This paper investigates the techno-economic viability of a grid-connected solar photovoltaic system combined with water flow glazing. An accurate assessment of the economic and energetic feasibility is carried out through simulation software and on-site tests on an actual prototype. The assessment also includes the analysis of global warming potential reduction. A prototype with WFG envelope has been tested. The WFG prototype actual data reported primary energy savings of 62% and 60% CO2 equivalent emission reduction when comparing WFG to a reference triple glazing. Finally, an economic report of the Photovoltaic array showed the Yield Factor and the Levelized Cost of Energy of the system. Savings over the operating lifetime can compensate for the high initial investment that these two technologies require.

Net-zero energy buildings (NetZEBs) are of a building typology designed to combine energy efficiency and renewable energy generation to consume only as much energy as produced onsite through renewable resources over a specified time. The successful creation of NetZEBs is crucial to combating the current climate crisis. Water flow glazing (WFG) is a key technology that will assist in achieving this goal. Several experimental facilities have been designed and constructed to collect data based on WFG technology. These experimental facilities demonstrate that the successful implementation of WFG will allow reducing heating and cooling loads, primary energy consumption, and CO2 emissions. However, a wrong WFG selection can lead to failure in NetZEBs design. The goal of this text was to assess WFG performance through key performance indicators to understand the need of other renewable energies so that the construction of NetZEBs becomes a realistic target.