Three is the magic number -- distance measurement of NGC 3147 using SN 2021hpr and its siblings

The nearby spiral galaxy NGC 3147 hosted three Type Ia supernovae (SNe Ia) in the past decades, which have been subjects of intense follow-up observations. Simultaneous analysis of their data provides a unique opportunity for testing the different light curve fitting methods and distance estimations. The detailed optical follow-up of SN 2021hpr allows us to revise the previous distance estimations to NGC 3147, and compare the widely used light curve fitting algorithms to each other. After the combination of the available and newly published data of SN 2021hpr, its physical properties can be also estimated with higher accuracy. We present and analyse new BVgriz and Swift photometry of SN 2021hpr to constrain its general physical properties. Together with its siblings, SNe 1997bq and 2008fv, we cross-compare the individual distance estimates of these three SNe given by the SALT code, and also check their consistency with the results from the MLCS2k2 method. The early spectral series of SN 2021hpr are also fit with the radiative spectral code TARDIS in order to verify the explosion properties and constrain the chemical distribution of the outer ejecta. After combining the distance estimates for the three SNe, the mean distance to their host galaxy, NGC 3127, is 42.5 $\pm$ 1.0 Mpc, which matches with the distance inferred by the most up-to-date LC fitters, SALT3 and BayeSN. We confirm that SN~2021hpr is a Branch-normal Type Ia SN that ejected $\sim 1.12 \pm 0.28$ M$_\odot$ from its progenitor white dwarf, and synthesized $\sim 0.44 \pm 0.14$ M$_\odot$ of radioactive $^{56}$Ni.Comment: 16 pages, 17 figures, 11 tables; accepted for publication in A&

Natural Ventilation for Energy Savings in California Commercial Buildings

This research program investigated the potential energy savings to be gained by retrofitting non-domestic buildings in California with natural ventilation for cooling. The simplest and most cost effective retrofit is to open windows on the façade and turn off any mechanical ventilation. To make the problem tractable attention was restricted to wind-driven natural ventilation. Stack-driven ventilation is likely to also be present in practice, and usually improves the cooling potential.The program was split into three major projects. Project 1 assessed the potential of and the barriers to the implementation of natural ventilation. Project 2 examined induced air movement and the possible ingress of outdoor pollutants. Project 3 produced new tools for predicting the energy performance of naturally ventilated buildings, and provided training in their use.The major barriers to the introduction are the lack of specific design guidance and a lack to easy-to-use modeling tools. These are compounded by a lack of design experience and case studies and the mandatory requirements for the amount and location of openable area specified in Title 24.Research on wind-driven natural ventilation using computational fluid dynamics and wind tunnel tests provided new algorithms for cross ventilation, single-sided ventilation and corner ventilation, accounting for opening size, location and number, and the effects of sheltering by neighboring buildings. These algorithms were implemented in EnergyPlus, and the new version of the code was used in three training sessions to provide the design and engineering community with some familiarity in the new modules that calculate natural ventilation.The overall outcome of this program is a comprehensive study of the current issues concerning retrofitting commercial buildings in California and an assessment of the potential risks and benefits. It has also significantly extended the capabilities for modeling, design, and operation of naturally ventilated buildings in California