Dynamic Mass Balance Model Research Articles

Ozone Chemistry on Greasy Glass Surfaces Affects the Levels of Volatile Organic Compounds in Indoor Environments.

The chemistry of ozone (O3) on indoor surfaces leads to secondary pollution, aggravating the air quality in indoor environments. Here, we assess the heterogeneous chemistry of gaseous O3 with glass plates after being 1 month in two different kitchens where Chinese and Western styles of cooking were applied, respectively. The uptake coefficients of O3 on the authentic glass plates were measured in the dark and under UV light irradiation typical for indoor environments (320 nm < λ < 400 nm) at different relative humidities. The gas-phase product compounds formed upon reactions of O3 with the glass plates were evaluated in real time by a proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometer. We observed typical aldehydes formed by the O3 reactions with the unsaturated fatty acid constituents of cooking oils. The formation of decanal, 6-methyl-5-hepten-2-one (6-MHO), and 4-oxopentanal (4-OPA) was also observed. The employed dynamic mass balance model shows that the estimated mixing ratios of hexanal, octanal, nonanal, decanal, undecanal, 6-MHO, and 4-OPA due to O3 chemistry with authentic grime-coated kitchen glass surfaces are higher in the kitchen where Chinese food was cooked compared to that where Western food was cooked. These results show that O3 chemistry on greasy glass surfaces leads to enhanced VOC levels in indoor environments.

Cadmium accumulation in soil resulting from application of biogas digestate and wood ash – Mass balance modelling

This study investigates the impact of substituting conventional NPK fertilizer with wood ash and biogas digestates at an agricultural field site in southwest Sweden. A three-year field experiment, comprising a crop rotation cycle of spring wheat, winter wheat, and oats, was conducted. The obtained results were employed to establish a dynamic mass balance model for the A horizon of the soil at the site. The Cd leaching term in the model was estimated using the Stockholm Humic model (SHM), which was recalibrated to accommodate low Cd concentrations by incorporating Cd complexation to thiol sites. The findings indicate that treatments receiving NPK fertilizer and biogas digestates experienced a net Cd loss, whereas treatments with wood ash demonstrated net Cd accumulation, attributed to its higher Cd content. Harvest yields were highest in the NPK treatment, and lower in two of the wood ash treatments, likely due to lower nitrogen additions in the latter. Cd offtake mirrored this trend, with the highest values in the NPK treatments and the lowest in the wood ash treatments, potentially also influenced by a pH difference of 0.2 units during the last year of the experiment. Geochemical modelling showed that Cd leaching is highly dependent on pH and that geochemically active soil Cd in the A horizon may have doubled between 1950 and 2002, due to elevated atmospheric deposition and fertilizer Cd during this period. Despite significant reductions in anthropogenic Cd fluxes since 2002, soil Cd has only decreased by 4%, showing the slow response of the soil pool to flux changes. Attaining a new steady-state after alterations in input fluxes will require hundreds of years. These results carry significance for determining sustainable application rates for recycled nutrient sources and underscore the crucial role of pH-dependent Cd sorption for Cd leaching.

Influence of shunt currents in industrial-scale alkaline water electrolyzer plants

The aim of this paper is to analyze through simulation how the energy efficiency of a single electrolysis stack at various loads is affected by shunt currents and to determine the energy-optimal load distribution between lines in a multiline electrolysis system under various magnitudes of shunt current losses. A dynamic energy and mass balance model of an industrial 3MW, 16bar alkaline water electrolyzer (AWE) process was developed using MATLAB. The optimization goal is to determine the power supply for each AWE line so that it can meet any hydrogen demand while minimizing the global specific energy consumption (SEC). The Particle Swarm Optimization (PSO) algorithm is used to minimize the objective function. According to the results of the single stack investigation, shunt current reduction could significantly improve the energy efficiency of partial-load operation. In addition, the optimization study revealed that whenever two or more lines are required to run in order to satisfy the hydrogen demand, the global SEC is minimized when the lines operate at equal loads.

Where does all the phosphorus go? Mass balance modelling of phosphorus in the Swedish long-term soil fertility experiments

To gain insights into phosphorus (P) dynamics in soils and the ability to predict soil responses to varying fertilizer inputs, mass balance models prove to be valuable tools. In this study, a new dynamic mass balance model, PBalD8, was used to describe the change in extracted P in the A horizon of soils subjected to diverse fertilizer treatments over a period of 50 to 60 years in five soil fertility experiments. The model employed a Freundlich equation to describe soil-solution partitioning of P and assumed that acid-lactate-extractable P represented a labile pool of P in instant equilibrium with soil solution P. Additionally, oxalate-extractable inorganic P was presumed to comprise the sum of the labile and stable pools of P, with mass flux to and from the latter described by Fick’s first law. The model was evaluated using results from extractions and P K-edge XANES spectroscopy. Notably, organic P, as revealed by P K-edge XANES, did not substantially contribute to long-term changes in soil P content and was therefore excluded from consideration. In general, the model offered reasonable fits to the extracted P concentrations. However, for the P-depleted treatments, a prerequisite was that the P removal through harvest was lower compared to measurements. Conversely, in three of the soils, the modelled fertilizer inputs needed to be reduced to 70 % to 85 % of the known additions. These discrepancies may be attributed to the involvement of deeper soil horizons, including deep crop uptake and mixing with lower soil layers, although other factors such as lateral dispersion and inaccuracies in estimating applied fertilizers cannot be discounted. These results underscore the necessity of gaining a more comprehensive understanding of how deeper soil horizons influence P mass balances in agricultural soils. In one of the soils, Fjärdingslöv, P K-edge XANES results demonstrated the formation of calcium phosphate over time in the highest fertilization treatment, consistent with the model. Additionally, in two soils, Kungsängen and the P-depleted Vreta Kloster soil, the model predicted a significant contribution from mineral weathering. However, the PBalD8 model also projected higher P leaching rates than those observed, suggesting that the model may not fully capture this P output term.

Global oceanic anoxia linked with the Capitanian (Middle Permian) marine mass extinction

The timing and causation of the Capitanian (late Middle Permian) biocrisis remain controversial. Here, a detailed uranium-isotopic (δ238U) profile was generated for the mid-Capitanian to lower Wuchiapingian of the Penglaitan section (the Guadalupian/Lopingian Permian global stratotype) in South China for the purpose of investigating relationships between the biocrisis and coeval oceanic anoxic events (OAEs). Negative δ238U excursions indicate two distinct OAEs, a mid-Capitanian (OAE-C1) and an end-Capitanian (OAE-C2) event. Mass balance modeling shows that the anoxic sink of uranium (Fanox; i.e., the fraction of the total U burial flux) and anoxic seafloor area (Farea; i.e., the fraction of total seafloor area) increased during each OAE. A dynamic mass balance model yields increases of Fanox from <30% to >60% and Farea from ∼1% to ∼4-7% during each OAE. These two OAEs coincided with two extinction episodes during the Capitanian biocrisis, supporting a causal relationship between oceanic anoxia and mass extinction during the Middle Permian. The most likely driver of middle to late Capitanian global warming and oceanic anoxia was episodic magmatism of the Emeishan Large Igneous Province.

Using a dynamic mass balance model to predict fate and transport of PCBs in a polluted boreal lake in Sweden

In 2013, a screening survey including fish (European perch, Perca fluviatilis) from 20 locations in the Stockholm region of Sweden indicated exceptionally high levels of PCBs (>450 ng ΣPCB7/g ww) in Lake Oxundasjön. An extensive sampling program was launched to define the magnitude and area of impact of PCBs. Moreover, a dynamic mass balance model approach was applied to identify and quantify key transport processes and predict the long-term turnover of PCBs given various remediation scenarios.Based on the dating of sediment profiles, primary emissions of PCBs to Lake Oxundasjön have likely occurred from the end of the 1940s until 1980, reaching the lake via one of its tributaries. Presently, the main source of PCBs is diffusion from the lake sediments. From the lake outlet, >400 g ΣPCB7/yr are transported to Lake Mälaren (the third largest lake in Sweden), supplying drinking water for parts of the Stockholm area. Remediation actions are necessary to reduce the PCB levels in fish below today's marketing limits and environmental quality standards. With natural recovery, our results indicate that the PCB levels in non-migratory fish from Lake Oxundasjön will be elevated for decades to come.The mass of PCBs stored in the lake sediments was estimated, and to our knowledge, Lake Oxundasjön is the most heavily PCB contaminated lake in Sweden. The system constitutes a unique opportunity to test and develop a mathematical mass balance model for PCBs, with substantial data acquired from different aquatic matrices. The model presented in the paper is applicable for risk assessments of PCBs, and the results contribute to the general understanding of the transport and turnover dynamics of PCBs in aquatic ecosystems.

Dynamic Mass Balance Modeling for Chemical Distribution Over Time in In Vitro Systems With Repeated Dosing.

As toxicologists and risk assessors move away from animal testing and more toward using in vitro models and biological modeling, it is necessary to produce tools to quantify the chemical distribution within the in vitro environment prior to extrapolating in vitro concentrations to human equivalent doses. Although models predicting chemical distribution in vitro have been developed, very little has been done for repeated dosing scenarios, which are common in prolonged experiments where the medium needs to be refreshed. Failure to account for repeated dosing may lead to inaccurate estimations of exposure and introduce bias into subsequent in vitro to in vivo extrapolations. Our objectives were to develop a dynamic mass balance model for repeated dosing in in vitro systems; to evaluate model accuracy against experimental data; and to perform illustrative simulations to assess the impact of repeated doses on predicted cellular concentrations. A novel dynamic in vitro partitioning mass balance model (IV-MBM DP v1.0) was created based on the well-established fugacity approach. We parameterized and applied the dynamic mass balance model to single dose and repeat dosing scenarios, and evaluated the predicted medium and cellular concentrations against available empirical data. We also simulated repeated dosing scenarios for organic chemicals with a range of partitioning properties and compared the in vitro distributions over time. In single dose scenarios, for which only medium concentrations were available, simulated concentrations predicted measured concentrations with coefficients of determination (R 2) of 0.85–0.89, mean absolute error within a factor of two and model bias of nearly one. Repeat dose scenario simulations displayed model bias <2 within the cell lysate, and ∼1.5-3 in the medium. The concordance between simulated and available experimental data supports the predictive capacity of the IV-MBM DP v1.0 tool, but further evaluation as empirical data becomes available is warranted, especially for cellular concentrations.

A dynamic nutrient mass balance model for optimizing waste treatment in RAS and associated IMTA system

The combination of a Recirculation Aquaculture System (RAS) and Integrated Multi-trophic Aquaculture (IMTA) aims to optimize the utilization of nutrient input by recycling aquaculture wastes through use as food resources for co-cultured species. The coupling of RAS and IMTA also allows the development of new aquaculture products, potentially increasing economic return. A dynamic nutrient mass balance model was developed for a seawater-based RAS system with a hypothetical IMTA component. The model incorporated a three-dimensional trophic food web (Atlantic salmon, Ulva lactuca and an invertebrate grazing species) alongside traditional mechanical and biological (nitrification) filtration processes. The model simulated different waste treatment methods using biological and mechanical filtration only and further incorporating macroalgae filtration. Simulations showed that RAS in combination with macroalgae IMTA could reduce dissolved inorganic nitrogen (DIN) by 66% and dissolved inorganic phosphorus (DIP) by 31% compared with just RAS biological filtration. Using an optimal harvesting strategy, DIN and DIP waste removal rose to 94% and 45% respectively, and an increase in by-products biomass of 41%. The dynamic nutrient mass balance model provides a quantitative tool to better understand the fate of nutrients, and to optimize the design of the system. Although the commercial-scale development of this type of aquaculture system will depend on feasibility and profitability, the concept of combining RAS and IMTA provides important potential for sustainable aquaculture in the future.

Dynamic energy and mass balance model for an industrial alkaline water electrolyzer plant process

This paper proposes a parameter adjustable dynamic mass and energy balance simulation model for an industrial alkaline water electrolyzer plant that enables cost and energy efficiency optimization by means of system dimensioning and control. Thus, the simulation model is based on mathematical models and white box coding, and it uses a practicable number of fixed parameters. Zero-dimensional energy and mass balances of each unit operation of a 3 MW, and 16 bar plant process were solved in MATLAB functions connected via a Simulink environment. Verification of the model was accomplished using an analogous industrial plant of the same power and pressure range having the same operational systems design. The electrochemical, mass flow and thermal behavior of the simulation and the industrial plant were compared to ascertain the accuracy of the model and to enable modification and detailed representation of real case scenarios so that the model is suitable for use in future plant optimization studies. The thermal model dynamically predicted the real case with 98.7 % accuracy. Shunt currents were the main contributor to relative low Faraday efficiency of 86 % at nominal load and steady-state operation and heat loss to ambient from stack was only 2.6 % of the total power loss.

Development and validation of a dynamic mass-balance prediction model for indoor particle concentrations in an office room

The Korean government recommends intermittent operation of air purifiers (APs) as a measure to maintain indoor particulate matter (PM) concentrations below the mandatory standards and reduce exposure to indoor PM2.5 (PM with a diameter smaller than 2.5 μm). However, there is no guideline to inform occupants of when and how long APs should be operated to comply with the standards. In this study, we developed a dynamic mass-balance model to predict indoor PM concentrations in an office considering penetration of outdoor particles, change in number of occupants, and operational status of the AP. The model fit and prediction accuracies were verified using the American Society for Testing and Materials (ASTM) D 5157 criteria and the k-fold validation technique. We observed that indoor PM2.5 concentrations were determined by infiltration of outdoor PM2.5, and indoor generation/resuspension by occupants and removal. For PM2.5-10 (2.5 μm < diameter <10 μm), the indoor concentrations were determined by interior door access and indoor generation/resuspension. The operation of an AP effectively decreased indoor PM2.5 concentration but not PM2.5-10. We found that our model accurately predicted indoor PM concentrations. Therefore, using the developed model, a guideline may recommend: 1) start the AP when the predicted indoor PM2.5 concentrations under no AP operation approached the standard (e.g., 90% of the standard); and 2) stop the AP when the indoor PM2.5 concentration predicted under the assumption of no AP operation fell below the standard (e.g., 80% of the standard).

The role of hydrology on enhanced weathering for carbon sequestration I. Modeling rock-dissolution reactions coupled to plant, soil moisture, and carbon dynamics

Enhanced Weathering (EW) resulting from soil amendment with highly reactive silicate minerals is regarded as one of the most effective techniques for carbon sequestration. While in laboratory conditions silicate minerals dissolution rates are well characterized, in field conditions the rate of the dissolution reaction is more difficult to predict, not least because it interacts with soil, plant, and hydrologic processes. Here we present a dynamic mass balance model connecting biogeochemical and ecohydrological dynamics to shed light on these intertwined processes involved in EW. We focus on the silicate mineral olivine, for its faster laboratory dissolution rate, and pay particular attention to understanding the role of plants and hydrological fluctuations and their propagation into soil biogeochemical processes (including cation exchange) and EW dynamics. A companion paper Cipolla et al.(2021) presents specific applications with the main purpose of understanding the carbon sequestration potential under different climate scenarios.

Performance characteristics of a fan filter unit (FFU) in mitigating particulate matter levels in a naturally ventilated classroom during haze conditions.

The performance of a low-cost fan filter unit (FFU) in mitigating hazardous particulate matter (PM) levels in a naturally ventilated school classroom is presented. The FFU can be considered as a simplified mechanical ventilation and air-conditioning system without heating and cooling functions. The FFU improves indoor air quality through introduction of cleaned outdoor air to flush out internally generated heat and moisture and reducing infiltration by maintaining indoor pressurization. Indoor particle number concentrations were reduced between 85% and 95%. The particle removal performance (PRFFFU ) of the FFU is determined and incorporated into the augmented façade penetration factor (Paug ). A case-specific recursive dynamic mass balance model is used to characterize the infiltration factor (FINF ), deposition rate (K), and the penetration efficiency (Paug ) from continuously monitored indoor and outdoor mass concentration levels. Computed "Paug " (0.07, 0.09, and 0.13) and "FINF " (0.06, 0.08, and 0.11), respectively, for PM10, PM2.5, and PM1 suggest that exposure to PM was significantly reduced indoors. The effectiveness of the FFU for reduced "FINF " and "Paug " may be attributed to its superior filtration, dilution, and exfiltration mechanisms. In comparison with alternative PM mitigation solutions, the FFU is effective, affordable, and sustainable.

A comparative study of the effects of ventilation-purification strategies on air quality and energy consumption in Beijing, China

In countries suffering from heavy ambient air pollution, ventilation is a problem, as ventilation intakes outdoor air pollutants, such as particulate matter with an aerodynamic diameter less than 2.5 um (PM2.5), while removing indoor air pollutants. Thus, it is important to identify appropriate ventilation-purification strategies to build healthy indoor environments with low energy consumption. This study reports the comparison of two sets of strategies, i.e., mechanical ventilation with filters and natural ventilation with indoor air cleaners, in respect to energy consumption and the PM2.5 and carbon dioxide (CO2) exposure of occupants in a typical apartment in Beijing, China. A dynamic mass balance model was employed to calculate the PM2.5 and CO2 exposure concentrations, while the energy consumption of heating and cooling was simulated with the Designer’s Simulation Toolkit. It was found that natural ventilation with air cleaners provided lower PM2.5 exposure compared with that of mechanical ventilation with filters; however, mechanical ventilation achieved a lower CO2 exposure concentration. The annual cooling, heating, and fan energy consumption of natural ventilation strategies are lower than those of mechanical ventilation strategies. With respect to natural ventilation, an infiltration rate of 0.3–0.4 h−1 was the preferred setting, which led to low PM2.5 and CO2 exposure with lower energy consumption. The basic requirements for controlling indoor PM2.5 could be met if the threshold is set at 25 µg/m3. The results provide guidelines on how to combine multiple ventilation purification strategies to improve indoor air quality with lower energy usage.

Application of dairy manure as fertilizer in dry land in East China: field monitoring and model estimation of heavy metal accumulation in surface soil.

Manure-based fertilizer is usually applied to agricultural soils to increase soil fertility and improve soil quality. However, this practice has an impact on the soil environment, e.g., increasing heavy metal contents. The aim of this study was to evaluate and estimate the accumulation tendencies of eight heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), manganese (Mn), and zinc (Zn) in a soil fertilized continuously with dairy manure through a 5 years' field-scale experiment. Contents of the As, Cd, Cr, Cu, Mn, and Zn gradually increased with the fertilization time of dairy manure at the stable rate of around 326 t hm-2 year-1, leading to annual mean increases of 3.6%, 2.4%, 3.9%, 3.8%, 4.2%, and 6.1%, respectively. Based on the prediction of a dynamic mass balance model using the current practice, the contents of Cd and Zn in the fertilized soil would reach the Chinese standard values for agricultural soils in 48 and 35 years. The mitigation measures, such as lower application rates, for the environmental risk of heavy metal accumulation should be considered.

Biotic Energy Flow Passing through the Microbial Trophic Web in the Pelagic Zone of Lake Ecosystems

An algorithm of a dynamic mass-balance model emulating the biotic energy flow in a planktonic community with the involvement of microbial organisms has been developed. The abiotic input parameters of the model are the latitude, mean depth of the water body, total phosphorus content, and water color. The model makes it possible to forecast the biomass and production of key plankton groups. It is shown that the food-base production for fish and their growth are determined by the degree of protozoan plankton involvement in the trophic web.

Development and optimization of a novel controller for regenerative indirect evaporative cooler

Abstract The main characteristic of an indirect evaporative cooler (IEC) is the high dependency on ambient air conditions. To ensure stable indoor temperature and provide better thermal comfort, proper control strategy is essential. However, very limited studies report the controller used in IEC. In this paper, a novel control scheme named high-low (H-L) is proposed for regenerative indirect evaporative cooler (RIEC). Under H-L control scheme, the fans would be switched between high speed and low speed rather than completely turned off. The H-L control adopts the multi-speed technology, providing energy saving potential compared with conventional on-off control and overcome the complexity and costly of variable speed technology. The annual performance of RIEC was simulated under H-L control based on the RIEC model and dynamic indoor heat and mass balance model. The influence of low speed to high speed ratio (L/H) is discussed in order to propose an optimal L/H by considering both the thermal comfort and annual energy consumption. The results show that the H-L control can provide stable indoor temperature and satisfactory thermal comfort with Predicted Mean Vote (PMV) in the range of -0.5 to 0.5 for 76.2% of time. The optimal L/H is found to be 0.25 to 0.33 because of high thermal comfort provided and lowest energy consumption.

Dynamic modeling of organic carbon fates in lake ecosystems

Lakes are active processors of organic carbon (OC) and play important roles in landscape and global carbon cycling. Allochthonous OC loads from the landscape, along with autochthonous OC loads from primary production, are mineralized in lakes, buried in lake sediments, and exported via surface or groundwater outflows. Although these processes provide a basis for a conceptual understanding of lake OC budgets, few studies have integrated these fluxes under a dynamic modeling framework to examine their interactions and relative magnitudes. We developed a simple, dynamic mass balance model for OC, and applied the model to a set of five lakes. We examined the relative magnitudes of OC fluxes and found that long-term (>10 year) lake OC dynamics were predominantly driven by allochthonous loads in four of the five lakes, underscoring the importance of terrestrially-derived OC in northern lake ecosystems. Our model highlighted seasonal patterns in lake OC budgets, with increasing water temperatures and lake productivity throughout the growing season corresponding to a transition from burial- to respiration-dominated OC fates. Ratios of respiration to burial, however, were also mediated by the source (autochthonous vs. allochthonous) of total OC loads. Autochthonous OC is more readily respired and may therefore proportionally reduce burial under a warming climate, but allochthonous OC may increase burial due to changes in precipitation. The ratios of autochthonous to allochthonous inputs and respiration to burial demonstrate the importance of dynamic models for examining both the seasonal and inter-annual roles of lakes in landscape and global carbon cycling, particularly in a global change context. Finally, we highlighted critical data needs, which include surface water DOC observations in paired tributary and lake systems, measurements of OC burial rates, groundwater input volume and DOC, and budgets of particulate OC.

A novel high-throughput method for kinetic characterisation of anaerobic bioproduction strains, applied to Clostridium kluyveri

Hexanoic acid (HA), also called caproic acid, can be used as an antimicrobial agent and as a precursor to various chemicals, such as fuels, solvents and fragrances. HA can be produced from ethanol and acetate by the mesophilic anaerobic bacterium Clostridium kluyveri, via two successive elongation steps over butyrate. A high-throughput anaerobic growth curve technique was coupled to a data analysis framework to assess growth kinetics for a range of substrate and product concentrations. Using this method, growth rates and several kinetic parameters were determined for C. kluyveri. A maximum growth rate (µmax) of 0.24 ± 0.01 h−1 was found, with a half-saturation index for acetic acid (KS,AA) of 3.8 ± 0.9 mM. Inhibition by butyric acid occurred at of 124.7 ± 5.7 mM (KI,BA), while the final product, HA, linearly inhibited growth with complete inhibition above 91.3 ± 10.8 mM (KHA of 10.9*10−3 ± 1.3*10−3 mM−1) at pH = 7, indicating that the hexanoate anion also exerts toxicity. These parameters were used to create a dynamic mass-balance model for bioproduction of HA. By coupling data collection and analysis to this modelling framework, we have produced a powerful tool to assess the kinetics of anaerobic micro-organisms, demonstrated here with C. kluyveri, in order further explore the potential of micro-organisms for chemicals production.

Comparative study of on-off control and novel high-low control of regenerative indirect evaporative cooler (RIEC)

The main characteristic of an indirect evaporative cooler (IEC) is its dependency on ambient air conditions. To ensure stable indoor temperature and provide better thermal comfort for the occupants, proper control strategy is essential. However, very limited studies report the controller used in IEC. Therefore, two control schemes are comparatively studied for regenerative indirect evaporative cooler (RIEC) application, including conventional on-off control and newly proposed high-low (H-L) control. Under on-off control scheme, the fans are either in operation at constant rated speeds or turned off if the indoor temperature is satisfied. While under H-L control scheme, the fans would be switched between high speed and low speed rather than completely turned off. The annual performance of RIEC was simulated under the two control schemes based on the RIEC model and dynamic indoor heat and mass balance model. The results show that the H-L control is superior to on-off control by providing better thermal comfort, better indoor air quality and 11.3% less energy consumption annually. The advantages of H-L control are mainly reflected in transition seasons with smaller indoor temperature variation range, lower switch frequency of the fan speed, smaller predicted mean vote (PMV) variation and longer fresh air guarantee.

Development of a nationally representative set of combined building energy and indoor air quality models for U.S. residences

Americans spend most of their time inside residences where they are exposed to a number of pollutants of both indoor and outdoor origin. Residential buildings also account for ∼20% of the primary energy consumed in the U.S. To provide a tool for future investigations of interactions between energy use and indoor air quality (IAQ) in homes across the U.S. population, we developed a custom set of nationally representative building energy and IAQ mass balance models that predict annual energy use for space conditioning and indoor concentrations of a number of pollutants of both indoor and outdoor origin across the U.S. residential building stock. The residential energy and indoor air quality (REIAQ) model framework is built in Python and integrates between EnergyPlus and a dynamic mass balance model. REIAQ utilizes historical weather data to predict hourly energy consumption, air change rates, and HVAC system runtimes, which are coupled with historical outdoor pollutant concentration data and assumptions for indoor emission sources and other factors to predict hourly indoor pollutant concentrations. Modeled indoor pollutants include PM2.5, UFPs, O3, NO2, and several volatile organic compounds (VOCs) and aldehydes. The REIAQ model set successfully predicted annual space conditioning energy consumption for the U.S. residential building stock within ∼2% of historical data. Modeled indoor concentrations, infiltration factors for outdoor contaminants, and indoor/outdoor ratios of each pollutant all matched closely with observations from prior field studies. Population-weighted annual average indoor pollutant concentrations were also used to estimate the chronic health burden of residential indoor exposures.