## 4 Results and Discussion  
In general, there are two climate change impacts that are directly linked to water-related building installations: the increased intensity of heavy rainfall and extreme heat waves. Table 2 summarizes the main measures to be adopted in buildings with a view to promoting the adaptation and resilience of buildings against these impacts. In the case of increased heavy rainfall intensity, it is necessary to adjust the design standards for new buildings and review the design of rainwater drainage in existing buildings. The latter aspect is more delicate with regard to rainwater siphonic systems [39], whose capacity to respond to unforeseen flow increases is smaller since it is known that, in these systems, a flow slightly above the design flow is sufficient to cause a rapid increase in the depth of water on the roof. Placing more emergency overflow outlets could be the solution. Reviewing the design standards should include new weather data and/or higher safety coefficients. Regarding extreme heat waves and the inherent risk of water scarcity, adjusting standards is again necessary, especially with regard to reviewing water tank sizing and increasing the efficiency of water \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Type of Climate Change Impact.** & \multicolumn{2}{c}{**Measures to be Adopted in Water-Related Instalations to Promote an Increased Resilience of the Building**} \\ \hline \multirow{4}{*}{Increased heavy rainfall intensity} & \multirow{2}{*}{**New Buildings**} & **Existing Buildings** \\ \cline{3-3}  & & - Review design standards by integrating new weather data or higher safety coefficients; & - Review rainwater drainage pipe sizing, especially stacks and drains (in gravity systems), and analyse the need for new emergency overflow outlets (specifically in national network). \\ \cline{1-1}  & - Construct green roads (preferably mandatory); & - Review rainwater drainage pipe sizing, especially stacks and drains (in gravity systems), and analyse the need for new emergency overflow outlets (specifically in national network). \\ \hline \multirow{4}{*}{Extreme heat waves (water scarcity)} & \multirow{4}{*}{
\begin{tabular}{} \end{tabular} } & - Review design standards considering greater capacity in water tanks (when they exist in the building). \\ \cline{1-1}  & & - Instal rainwater harvesting systems and/or greywater reuse systems; \\ \cline{1-1}  & - Apply water-efficient products (preferably mandatory). & - Apply flow or volume reducers. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measures to be adopted for promoting the adaptation and resilience of buildings against climate change impacts. Figure 4: Portuguese weather stations with information available. use in buildings. Rainwater harvesting and greywater reuse should be promoted, with this being the first solution particularly suited to answer the many impacts of climate change because it simultaneously reduces the flood peaks in urban areas and promotes additional water storage in buildings. The combination of green roofs and rainwater harvesting systems in buildings seems to be a very promising constructive solution, but this technology requires a refined knowledge of runoff coefficients, which show great variability due to roof characteristics and local climatic conditions. It is therefore important to determine reference values in each specific climate region for the design of these combined solutions, improving knowledge in this field that currently boils down to indicative values in some standards, and which research has shown to be non-generalizable. Following on from previous research, which led to a formula for determining monthly runoff coefficients (\(C_{M}\)) in Portugal, applicable to extensive green roofs, we sought to analyse the variability of their values across the territory.