A top-down approach for setting climate targets for buildings: the case of a New Zealand detached house

Czech Building Stock: Renovation Wave Scenarios and Potential for CO2 Savings until 2050

One of the major anthropogenic sources of greenhouse gases is the operation of building stock. Improving its energy efficiency has the potential to significantly contribute to achieving climate change mitigation targets. The purpose of this study was to roughly estimate such potential for the operation of the national building stock of Czechia to steer the national debate on the development of related national plans. The estimation is based on a simplified energy model of the Czech building stock that consists of sub-models of residential and nonresidential building stocks, for which their future energy consumptions, shares of energy carriers and sources, and emission factors were modeled in four scenarios. Uncertainties from the approximation of the emission factors were investigated in a sensitivity analysis. The results showed that the operation of the Czech building stock in 2016 totaled 36.9 Mt CO2, which represented 34.6% of the total national carbon dioxide emissions. The four building stock scenarios could produce reductions in the carbon dioxide emissions of between 28% and 93% by 2050, when also considering on-side production from photovoltaics. The implementation of the most ambitious scenario would represent a drop in national CO2 yearly emissions by 43.2% by 2050 (compared to 2016).

Setting Better-Informed Climate Targets for New Zealand: The Influence of Value and Modeling Choices

Quantifying greenhouse gas (GHG) emissions and setting GHG emissions budgets for anthropogenic systems are influenced by several value and modeling choices. This study, for the first time, quantified the influence of choice of GHG accounting approach, GHG metric, time horizon, climate threshold, global emissions budget calculation method, and effort-sharing approach, taking New Zealand (NZ) as a case study. First, NZ's production- and consumption-based emissions were quantified using multiregional input-output analysis and applying different GHG metrics (global warming and temperature potentials) and time horizons (20 and 100 years). Second, global emissions budgets for 1.5 °C, 2 °C, and 1 W m^-2 climate thresholds were estimated. Budget shares were then assigned to NZ using two effort-sharing approaches (grandfathering and economic value), and emissions were benchmarked against the assigned shares. Finally, the analysis was undertaken at the NZ sector level. The results showed that, for each GHG accounting approach, NZ's total emissions exceeded their budget shares, irrespective of the choices; the largest source of uncertainty was the choice of global emissions budget calculation method, followed by GHG metric, climate threshold, effort-sharing approach, and reference year for the grandfathering approach. The sector-level analysis showed that, while most sectors exceeded their budget shares, some performed within them. The ranking of uncertainty sources was quite different at the sector level, with the choice of effort-sharing approach providing the largest source of uncertainty. Overall, the study indicates the importance of handling value and modeling choices in a transparent way when quantifying GHG emissions and setting emissions budgets for anthropogenic systems.

Carbon Benchmark for Czech Residential Buildings Based on Climate Goals Set by the Paris Agreement for 2030

This paper deals with the problem that actual building regulations do not reflect the climate targets set by the Paris Agreement. To address this, a benchmark was developed for greenhouse gas (GHG) emissions of buildings on the basis of the Emissions Gap Report. We first applied an equal allocation of the GHG emission limit for 2030 among the forecasted population to calculate a virtual personal GHG emission limit. We took a proportion of this personal limit for the purpose of housing and extrapolated it for the whole building based on the number of occupants. We also undertook a case study of an actual multifamily residential building and compared its standard design to the benchmark using a simplified life cycle assessment (LCA) method in line with the national SBToolCZ method. The results showed that the assessed residential house exceeded the emission requirement by a factor of 2.5. Based on the assessment, six sets of saving measures were proposed to reduce the operational and embodied GHG emissions. The saving measures included change in temperature zoning, improvement of the U-values of the building envelope, exchange of construction materials for reduced embodied GHG emissions, exchange of heat source for biomass boiler, introduction of light-emitting diode (LED) lighting, use of mechanical ventilation with heat recovery, addition of vacuum solar collectors, and the addition of photovoltaic (PV) panels. Finally, the variants were compared and their suitability in the Czech conditions was examined.