Passive Environmental Control at Neighborhood and Block Scales for Conservation of Historic Settlements: The Case Study of Huatzai Village in Wang-An, Taiwan

Abstract

Climate change has gradually become a great challenge for heritage conservation. This study demonstrated that a hierarchal strategy corresponding to the scale of climate or weather date can be an alternative approach to making heritage conservation more efficient and sustainable. Therefore, the passive environmental control strategies at neighborhood and block scales are developed to effectively connect climate actions, normally at global or city scales, and the traditional preservation methods at building scale. The research results reflect the same conclusion as previous studies in that wind is the key factor affecting degradation mechanisms on heritage assets. Moreover, the adoption of weather data is a critical factor that influences the accuracy of computational fluid dynamics (CFD) simulation results of the detailed regional wind performance, which is supportive for strategy development. According to the simulation results, the study site, Huatzai village, with neighborhood-scale strategy can gain an improvement in overall wind impact. The velocity reduction is more than 70% in the windward areas. The block-scale strategy with the reuse of existing structures can bring 90% velocity reduction for the wake areas and the high-risk zones with strong turbulence.

1. Introduction

Climate change has increasingly attracted interest at research and policy levels. In the architecture, construction and engineering (ACE) industries, there have been many related studies discussing the impact that climate change would bring to new constructions and existing buildings. Many interdisciplinary and intergovernmental studies have been exploring the threat of climate change to cultural heritage sites as well. The Intergovernmental Panel on Climate Change (IPCC) [1] has published a series of weather databases and predictions, in which the emission scenario A1B and RCP 4.5 are widely employed [2,3], to clarify what level of risk is acceptable. It provides a solid base for experts to develop more comprehensive climate adaptation. However, a lot of those data are at global and city scales with low resolution, which are not clear enough to assess the detailed environmental impact around a site or a building, not to mention fragile historical buildings or heritage sites. Knowing the importance of regional data, the European Union (EU) conducted a project named “Climate for Culture” [4] to focus on the development of detailed regional climate models with high resolution to enable building-scale simulations to produce more credible estimates.

In response to the challenge of climate change, many climate adaptations or actions has been developed, including the well-known global goals called sustainable development goals (SDGs) and sustainability policies in many countries. However, for heritage conservation, most strategies are still based on traditional methods and focus on studies to reduce direct physical effects on the buildings or structures. As noted in the recommendations from the Scientific Council Symposium on Cultural Heritage and Global Climate Change [5], heritage conservation requires considering the potential loss that may occur due to detailed local climate characteristics and then determining the level of influence of each aspect of a site. The evaluation at site level is essential and also plays a significant role in connecting city-scale climate actions with building-scale preservations.

According to the research by Merlier et al. [6], which clearly defined the association between urban meteorology (urban physics) and urban spatial analysis (Figure 1), to correspond to the local (micro-scale) weather data, the spatial scale of heritage conservation is at district, neighborhood and block scales. To connect traditional building-scale preservation methods to climate action at city scale, the of conservation strategies at neighborhood and block scales are expected to be developed by considering detailed district-scale environmental performance.

Compared to new or existing buildings, the existing climate adaptions or strategies are difficult apply to heritage sites because of the heritage preservation regulations. The regulations strictly stipulate the principle of intervention level. The involvement of the passive environmental control idea is a promising solution. As the heritage site conservation level is higher, the conservation measures need to shift relatively to adopt more passive environmental control ideas.

Based on the above, this study argues that a hierarchal strategy corresponding to the scale of climate or weather data can be an alternative approach to carry out a more holistic, sustainable and locally adapted form of heritage conservation when facing the climate change issue. The relationship in spatial scale between the heritage conservation and meteorology, illustrated in Figure 2, shows that there is a gap between heritage conservation at city scale and building scale. Therefore, this study tries to develop conservation strategies at neighborhood and block scales by considering detailed regional environmental performance. The concept of passive environmental control is also employed by giving preferential consideration to natural resources and existing artificial resources to minimize the level of human intervention and achieve low-cost maintenance.

2. Methodology

2.1. Research Structure

The report published by International Council on Monuments and Sites (ICOMOS) [7] evaluated the effects of climate on six categories of cultural heritage sites and indicated that “wind” is a key weather factor affecting heritage buildings. Many wind characteristics (e.g., wind pressure, wind velocity, and being loaded with water, salt, and sand) have been demonstrated to increase the weathering, erosion, and denudation of heritage sites [8,9,10,11,12,13]. Therefore, Huatzai village, a heritage site facing a sever environmental challenge of strong wind, is selected as the case study.

As mentioned in the recommendation by ICOMOS [5], highly scientific tools are also considered a great potential means for heritage conservation. This study adopts the computational fluid dynamics (CFD) tool to gain a more detailed understanding of wind distribution in the site, which has been applied in many other research studies as well [14,15,16,17]. One of the advantages of CFD is the application of multiscale computation that is helpful to gain a more comprehensive understanding of environment performance and clarify the main causes. Moreover, its visualization performance is a more efficient means of evaluation to enable designers and planners to gain a more rapid understanding, compared to numerical forms of data

This study is divided into four phases (Figure 3): Phase Ⅰ—Data Collection, Phase Ⅱ—Wind Performance Analysis, Phase Ⅲ—Strategy Development, and Phase Ⅳ—Strategy Evaluation. Each phase has two to four tasks. In Phase Ⅰ, there are four tasks. The first one is the morphology analysis of Huatzai village, since many studies in the literature indicate that wind flow is considerably affected by spatial morphology, such as building height, building shape, road width, and road patterns [18,19,20,21]. The second task is weather data collection. The data from the weather station in the settlement can represent the weather characteristics of the village, but it is not appropriate for simulation models. Therefore, the weather data at the airport near the north side of the village is adopted to make the simulation in phase Ⅱ more credible. The third task is the survey of building damage. It is helpful to identify the weather effects on the buildings or structures physically. The final task is the collection of social and cultural information that might influence site layout or intervention level, such as the traditional living style and the level of preservation based on the local regulations

In Phase Ⅱ, the performance of the wind field around and in the site is discussed. A district-scale CFD simulation with current layout is conducted to assess the relationship between the site morphology, building damage, airflow distribution and weather condition in Huatzai village. The high-risk zones and spots can then be easily pointed out, which is a credible reference for strategy development in the next phase.

In Phase Ⅲ, passive environmental control strategies are developed. There is much research which has demonstrated that trees or plants can influence wind velocity and direction [22,23,24,25]. Therefore, plants are employed to create wind breakers or wind directors for the neighborhood-scale strategy. The block-scale strategy is developed by reusing the existing structures in the site.

In the final phase, the strategies in Phase Ⅲ are evaluated by CFD simulations to assess their effectiveness in reducing strong wind impact. The research workflow and all tasks for each phase are illustrated in Figure 3.

2.2. Pattern of Huatzai Village

Huatzai village is located on Wang-an Island, which is the fourth largest island in Penghu County and located in the southern Taiwan Strait. Wang-an Island is surrounded by the sea, and its terrain is flat and monotonous, without mountains or rivers. The coast comprises frequent curves, and the adjacent sea contains numerous reefs. Reaching an elevation of 53 m, Mount Tian-tai is the highest hill on the island. Huatzai comprises a total area of approximately 217 hectares and is mainly located in the west-central valley of Wang-an Island. Developed according to its natural topology and clan distribution, the Huatzai settlement has a circular pattern formed with living spaces, such as historical house clusters and Tsai-te-a (vegetable houses), constructed around a Hua-Xin, or “village heart”, denoting the small hill rising in the center of the settlement (Figure 4a). Most of the building clusters near the sea are sea-facing for wind protection. Therefore, the buildings are generally east-facing and side by side. The building cluster in east-south area (Shanzhaihou) is relatively scattered, and the buildings are generally east-facing. The main north–south road runs through the entire settlement. The cluster in the north-east (Dingliao) is located on the slope and has relatively clear topographical variations; the majority of the buildings are south-facing. An east–west path was established part way up the slope. The westbound section of the path, leading to stone fish weirs, faces a marine landscape, and the eastbound section leads to the side of the mountain. The east–west path is much narrower than the north–south road. Onsite observation revealed that the layout pattern of the Huatzai settlement on Wang-an differs only slightly between its early days and today (Figure 4b,c). Two north–south main paths run through the settlement. In addition, the east–west road to the north of Hua-Xin is a main path within the settlement.

2.3. Computational Fluid Dynamics Simulation Settings and Validation

The boundary settings of the CFD simulation in this study are set based on the recommendation in COST Action 732 [29], which lists detailed settings for different CFD simulation model types to ensure accurate simulation results. In addition, the RNG K-ɛ turbulence model, which is suitable for multi-scales, is set according to the results of prior studies [30,31,32,33,34].

Regarding the inlet setting, airflow close to the ground is extremely affected by land surface roughness (e.g., buildings and structures), which easily gives rise to turbulence. As the height of the wind increases, the turbulence gradually weakens. Therefore, it is necessary to set the wind profile as the simulated inlet. The direction and velocity of the inlet is set as 30° and 11.3 m/s, referring to the data from Wang-an airport.

The grid size of of CFD simulation is mainly determined according to differences in elevation of the terrain as well as the dimensions of the house openings. Therefore, the grid size in this study is set to 0.8 m × 0.8 m. In addition, to reduce computation time, the borders of the settlement on all sides are initially set to widen outward and upward at a ratio of 1.02. The final model comprises 49,238,568 grids. For the grid sensitivity test, the difference for each measured point between the model with adopted grid and the one with 1.5 times finer grid size are all within 1%. For the validation, the averaged difference rate is less than 10% between the data in the simulations with adopted settings and the data from the weather station in the settlement. The results of the gird sensitivity test and validation both prove that the settings of the CFD model are reliable.

3. Result and Discussion

3.1. Phase Ⅰ—Data Collection

3.1.1. Characteristic Spaces in Huatzai Village

The Tsai-te-a (vegetable houses) mentioned in Section 2.2 are observed as a characteristic part of living spaces in Huatzai settlement. They are mostly located near the main building clusters and also spread out in the north area of the settlement, as displayed in Figure 5a. These houses are formed by 70- to 170-cm high and 40-cm thick windbreak walls built to prevent wind damage. Most of these spaces are used to grow leafy vegetables and fruits, such as cabbage, corn, sorghum, and melons. Not only for planting, Tsai-te-a were also used for family development historically; when a new family was established, their main building was built on the land to replace the Tsai-te-a. Today, Tsai-te-a have generally been abandoned, with the exception of a few alongside main buildings (family house) that maintain crop planting (Figure 5b).

3.1.2. Weather Conditions

According to the Penghu.info website [35], which lists the overall meteorological conditions for Wang-an Township, the local average temperature for Wang-an is 23 °C. The lowest average temperature occurs in January (17 °C), and the highest occurs in July (29.5 °C). The yearly distribution of precipitation is extremely uneven, with precipitation generally concentrated in the months between the fourth and ninth months of the lunar calendar year. Furthermore, the data from the weather station indicate that winds in the Huatzai settlement are most frequently northwest winds, often occuring in July, August, and September, while southeast winds often occur in May.

For simulations, the wind data inside the village are not suitable to be adopted, because the data have been influenced by the morphology of settlement. Therefore, to make the district-scale simulation result more credible, the data outside the settlement are adopted. This study applied the wind data from Wang-an airport, located near the north side of the Huatzai settlement. The data is different from the weather station inside the settlement. The winds are most frequently north-northeast with an average velocity of 11.3 m/s.

3.1.3. Building Damage Review

The official restoration of the Huatzai settlement began in 1980. After the village was included in the list of 100 most endangered sites by the World Monuments Fund in 2003, Huatzai gradually gained attention from various sectors. In 2012, the project initiated by the Bureau of Culture of Penghu [26] systematically evaluated the present situation and damage causes of the historical houses in the settlement. A comprehensive evaluation of restoration reports revealed that reviews on the subject have generally focused on the structure of the historical houses. A preliminary summary of the main damage to the buildings and the damage conditions is presented in

Table 1. Main causes of damage and data on the deterioration of walls of different orientations in historical houses in Huatzai village.

Damaged Component	Damage	Deterioration of Walls of Different Orientations (Hardness ≤ Level 3)
Surface and frame of the roof	Erosion Wooden structure collapse due to moisture-induced decay Plant breeding Insect eating
Wall structure	Collapse due to water vapor penetrating upward from the ground
Wall surface	Erosion
Doors and windows	Moisture-induced decay Strong wind–driven damage to part of the ancient houses

.

The research by Chung [13] employed the Schmidt hammer to test the hardness value of the walls of the houses onsite and to determine the level of deterioration of buildings with different orientations in the settlement. Based on the research results, the wall orientations were ranked according to the number of walls with a hardness below grade 3, with the result of NW > E > N > NE > S > W > SE > SW, as presented in Table 1. By comparing this to the wind data in the village, which are most frequently northwest winds, it can be proved that there is a direct correlation between structure erosion and the frequency of wind direction and velocity.

3.1.4. Preservation Level of Buildings

The local government has regulated preservation levels for the Huatzai settlement. These levels are divided into six categories. The first level is assigned to buildings with the highest level of preservation; these buildings cannot be added onto or demolished, and their original appearances must be preserved. Moreover, no alteration is allowed with respect to construction methods, building components, and decoration. There are approximately 55% of the buildings in Huatzai village are identified as belonging to the first preservation level, excluding new buildings and those that were completely destroyed.

3.2. Phase Ⅱ—Wind Field Performance Analysis

3.2.1. Wind Path Analysis

According to the simulation results, the morphology and the buildings of the settlement caused the prevailing wind from the northeast to flow along the east and west border of the settlement, as illustrated in wind paths A and B in Figure 6. Once the prevailing wind moved into the settlement, it primarily flowed along the main lanes, as illustrated in paths C, D, E, F, and G in Figure 6, and the wind direction shifted from 30° to parallel with the settlement roads (resembling a north wind). The building topology around the Hua-Xin caused the direction of the air flow to gradually shift toward the southeast, as illustrated in paths I and H in Figure 6. This precisely matches the survey results discussed in Section 3.1.3; the proportion of hardness deterioration was high in the northeast walls of the buildings [13] (Table 1). This demonstrates that the structural strength of windward walls can be affected by a long-term wind flow, even when its velocity is not high enough to cause immediate damage.

On the other hand, the result also revealed the importance of the weather data adoption for the simulation model. The topography, terrain, and morphology of the site had a huge influence on the wind path. The simulations at different scales need to consider these factors to avoid adopting inapplicable data that causes unreliable results. In this study, the weather data of the inlet in the simulation model were from the station outside the settlement, where there are no tall obstacles around the station. The simulated data were less than 10% different from the data in the station inside the settlement.

3.2.2. High-Risk Designation

Generally, only winds with a velocity of 15 m/s or more can cause immediate structural damage to buildings. However, erosion is accelerated and a risk of material deterioration can appear if a building is continuously struck by winds in a fixed direction, which was proved in Section 3.1.3 and Section 3.2.1. Therefore, the Central Weather Bureau’s strong wind standard of 10 m/s was adopted to identify hot spots with a high risk of erosion. Based on the simulation results (Figure 7), it can be deduced that the climate had already been considered by the time of site selection for the settlement. The hill to the north of the settlement effectively weakened strong winds before they reached the settlement, generally controlling the average wind velocity to below 10 m/s. However, some areas of the settlement still faced high-speed winds due to the topography and the arrangement of the buildings. According to the air flow characteristics, the settlement can be divided into five main wind zones. Zone A directly faced the prevailing wind and was therefore most affected by strong winds. Zone B was affected by the relatively elevated terrain of the Hua-Xin, and the wind velocities on both sides of Zone B were significantly higher. In Zone C, with the exception of wake areas where the wind velocity was higher, the reduced density of buildings in the zone leads to Venturi and corner effects. Because nothing blocked the east of the settlement, Zones D and E were susceptible to the influence of air flows. The unclassified areas were low-wind zones. Point A1—A12, B1—B5, D1—D2, and E1, indicated in Figure 7, were potential high-risk spots.

3.3. Phase Ⅲ—Strategy Development

3.3.1. Strategy A

For the Huatzai settlement, two strategies were proposed, namely Strategy A at the neighborhood scale and Strategy B at the block scale. For Strategy A at the neighborhood scale, an onsite survey revealed that several locations to the north, northeast, and east of the settlement either had no buildings or the initial buildings had collapsed and were completely destroyed due to the strong wind in the areas. With the exception of the northbound access road, which had Norfolk Island Pine Trees (Araucaria excelsa) lining the road on both sides, the area was nearly completely covered in White Popinac (Leucaena leucocephala). Therefore, a windbreak was planned to block the north, northeast, and east from the strong wind with northeast direction. The windbreak comprised Norfolk Island Pine Trees, which are common on Wang-an Island. The trees were regularly distributed to surround the highlighted blocks displayed in Figure 8a.

3.3.2. Strategy B

The Tsai-te-a (vegetable houses) are kinds of extended living spaces in the Huatzai settlement. In the current state, only a small number of them are still used by residents for farming. The majority of the Tsai-te-a are abandoned and covered with wild plants. The stipulations of the “Overall Review Plan for the Preservation and Redevelopment Plan of the Huatzai Settlement, an Important Settlement in Wang-an, Penghu County” [32] allows for a windbreak to be installed around Huatzai settlement. For the structures or vegetable houses in the settlement that had been completely abandoned, plants could be added for green beautification, and simple leisure facilities with landscaping are also allowed to be installed. Based on the observation in Phase I, the distribution and location of the Tsai-te-a initially appeared to be scattered within the settlement. However, the location and distribution were highly correlated with the wind field characteristics. The locations of most of the Tsai-te-a enabled them to partially prevent the historical buildings from being affected by strong wind (Figure 8b). Therefore, for Strategy B at the block scale, Tsai-te-a were considered as a means of improving the high wind velocity areas in the Huatzai settlement.

3.4. Phase Ⅳ—Strategy Evaluation

Regarding the simulation results of Strategy A, the results indicated that plants arranged on the windward side can considerably affect airflow paths and reduce the wind velocity in the settlement (Figure 9). The wind velocities in Zone A were reduced by more than 70% to less than 3.5 m/s, listed in

Table 2. Comparison of velocity between current state and Strategy A.

(a) Zone A
Check Points	A1	A2	A3	A4	A5	A6	A7	A8	A9	A10	A11	A12
Current State (m/s)	9.51	9.32	11.67	12.77	12.47	10.24	9.88	9.48	9.54	10.12	10.24	10.17
Strategy A (m/s)	0.06	2.5	3.4	1.58	0.52	0.88	0.63	1.09	0.47	0.62	0.56	0.57
Reduction (%)	99%	73%	71%	88%	96%	91%	94%	88%	95%	94%	94%	94%
(b) Zone B
Check point	B1		B2			B3		B4		B5
Current State (m/s)	10.2		9.77			9.54		9.62		9.56
Strategy A (m/s)	0.18		4.11			8.36		9.4		8.12
Reduction (%)	98%		58%			12%		2%		15%
(c) Zone C, D and E
Check point	C1		C2		C3	D1		D2		E1
Current State (m/s)	9.5		9.69		9.72	9.66		9.53		9.94
Strategy A (m/s)	5.82		2.93		5.81	8.26		6.17		6.06
Reduction (%)	39%		70%		40%	15%		35%		39%

. Then, the topology of the Hua-Xin caused the wind velocity to become even lower (points B1 and B2). However, the effect of plants on Zone B was not great as on Zone A. The wind velocities at points B3, B4, and B5 by landscape design outside the settlement proved difficult and only reduced the velocity by 2–15%, while the values were all larger than 8.12 m/s (Table 2). The wind velocity in Zone C, as expected, was decreased due to the plant arrangement. In Zones D and E, the speed-reducing effect was relatively limited because the arranged plants turned weak on the east-facing area (Table 2).

For Strategy B, in which Tsai-te-a were employed as a speed-reducing means, the overall wind field conditions barely changed, as illustrated in Figure 10. However, the high-risk spots were clearly affected. It was proved again that the local residents developed the form of Tsai-te-a to adapt to the environment by their living experience. Because of the varied wind field conditions that different areas faced, the extent to which the Tsai-te-a reduced the wind velocity in various areas and spots was varied and exclusive, as shown in

Table 3. Velocity between current state and Strategy B.

(a) Zone A
Check Points	A1	A2	A3	A4	A5	A6	A7	A8	A9	A10	A11	A12
Current State (m/s)	9.51	9.32	11.67	12.77	12.47	10.24	9.88	9.48	9.54	10.12	10.24	10.17
Strategy B (m/s)	1.36	5.82	6.24	6.33	12.29	4.51	8.65	8.08	7.94	8.1	8.96	3.84
Reduction (%)	86%	38%	47%	50%	1%	56%	12%	15%	17%	20%	12%	62%
(b) Zone B
Check point	B1		B2		B3			B4		B5
Current State (m/s)	10.2		9.77		9.54			9.62		9.56
Strategy B (m/s)	1.01		2.4		7.15			8.13		7.91
Reduction (%)	90%		75%		25%			15%		17%
(c) Zone C, D and E
Check point	C1		C2		C3		D1	D2		E1
Current State (m/s)	9.5		9.69		9.72		9.66	9.53		9.94
Strategy B (m/s)	9.07		8.03		1.47		6	6.29		7.89
Reduction (%)	4%		17%		85%		38%	34%		21%

.

Both Strategy A and Strategy B proved the effectiveness of wind reduction. However, the strategies at different scales played different roles. Based on the simulation results and comparisons shown in Figure 9, Figure 10 and Figure 11, Strategy A can affect overall wind distribution in the settlement at neighborhood scale with a windbreak, especially the windward areas (e.g., Zone A and right side of Zone C). Relatively, in the wake-flow areas (west side of Zone C and Zone E), the effect of Strategy B was stronger than that of Strategy A. Compared with other zones, the airflow in Zone B was more complicated due to the strong effect of the small hill in the center of the settlement (Hua-Xin). Strategy B could generally induce a greater wind decrease than Strategy A (Figure 11b). To sum up all the simulation results, for Huatzai village, the combination of adding windbreaks in the windward areas of the settlement and adding Tsai-te-a in the wake areas and the high-risk spots with strong turbulence could be the most efficient arrangement.

4. Conclusions

For cultural heritage sites or historic buildings, it is highly difficult to develop a universal climate adaptation strategy since there are strict limits set by preservation regulations. This study argues the strategies at different spatial scales corresponding to meteorology scales could be an alterative approach. To correspond to the microscale climate, the strategies combined with passive methods at neighborhood and block scales can be treated as the first line of defense to absorb the impact of climate change.

Due to the huge effect of wind on architectural heritage indicated in the research, this study took Huatzai village, facing the threat of strong wind, as the case study. The neighborhood-scale and block-scale passive environmental control strategies were developed through landscape design and reuse of existing structures to reduce the impact of strong wind. The feasibility of these strategies was determined through a series of CFD simulations. The main conclusions derived from the simulation results are as follows:

A.

Weather data adoption must consider the scale of the analyzed spaces.

The simulation results in Task 6 demonstrate that the patterns and arrangements of buildings and terrain inside the settlement affected the airflow directions and wind velocities. The wind performance in Zones A, B, C and D shows different characteristics. Therefore, the traditional method of drawing up the building preservation using regional weather data might not be precise enough to improve the impact of the main factors that cause high velocities.

Accordingly, to enable an accurate and detailed understanding of the wind field conditions in the settlement, weather data that are unaffected by settlement pattern data should be used as input for the CFD models, wind tunnel tests or other tools. Such data could be gained from the weather stations installed around the periphery of the settlement. The simulated wind velocities in Task 6 showed less than 10% difference from the data collected from the weather station in the settlement.

B.

Wind is a key factor that affects degradation mechanisms on heritage assets.

The comparison of the survey collected in Task 3 and the simulation result in Task 6 proves that there is a direct correlation between structure erosion and the frequency of wind direction, which also matches ICOMOS’s research result [7], indicating that wind can transport pollutants, salts, moisture, and sand that lead to surface abrasion, increased water penetration, structural damage and potentially the collapse of structures.

C.

Settlement arrangement and lifestyle reviews are essential for climate adaptation strategy development.

Based on the simulation result in Task 10, the arrangement of Huatzai settlement partly reflects local residents’ responses to the local environment. The vegetable houses in Huatzai village, Tsai-te-a, obviously reduce the velocity and decreases the impact of strong wind on the main buildings, although they are not qualified to be preserved. Developing climate adaptation strategies by learning from indigenous inhabitants increases the feasibility of the strategies and also preserves the local intangible culture assets.

D.

Hierarchal climate adaptation strategy could bring more efficient heritage conservation.

Based on all of the simulations in this study, a hierarchal climate adaptation strategy could be drawn up. A detailed environment performance at district scale by consider microscale weather data could efficiently point out the high-risk zones and spots and identify the characteristics of airflow in those zones. Then, according to those characteristics, a corresponding strategy with different scales could be developed precisely.

It is proved that the strategy at neighborhood scale with a windbreak can affect overall wind distribution in the settlement, especially for the windward areas. The highest velocity reduction in the study is about 99%. The strategy at block scale can cause better improvement in the wake areas and specific spots with strong turbulence with the best reduction of 90% in this study.

In conclusion, the passive environmental control strategies at neighborhood and block scales could prevent immediate damage to buildings due to sudden high wind velocities and alleviate the weakening of the material strength of the buildings caused by long-term strong winds. This would subsequently reduce the frequency of renovation work and facilitate both short-term and long-term conservation and building preservation.