Swedish Study Offers a Method for Gauging Suitability of Solar Deployment on Historic Buildings

published: 2019-11-19 14:36 | editor: | category: News

Is it acceptable to deploy solar PV at sites of cultural significance? The general public over time has become more accepting of solar panels on roofs of different types of buildings as PV technologies improve in efficiency. However, attempts to have heritage buildings powered by solar energy can still bring about some controversy. The designs of mainstream solar panels have yet to evolve to the point where they can integrate seamlessly into the highly ornamental and fragile facades of historic or culturally distinctive buildings. Based on popular opinions, the speckled blue color of solar panels tends to jump out and seriously diminish the aesthetic quality of an architectural work. Thus, their presence would work against the preservation of the cultural values of heritage buildings.

Although there are now increasing efforts from the public and private sectors to introduce renewable energy solutions to the fields of architecture and construction, progress is limited when it involves historic buildings and monuments. Unlike modern residential and commercial buildings, heritage buildings embody unique material and cultural legacies that cannot be replicated. When a heritage building suffers physical damages or has its appearance affected in any way, its historical context and values will be lost. Hence, to have heritage buildings contribute to the reduction of carbon emissions and incur less energy costs will require further innovations in the development of renewable energy technologies.

In Taiwan, the protection and maintenance of heritage buildings is regulated under the country’s Cultural Heritage Preservation Act. This law stipulates that any discovery of a possible archaeological or heritage site has to be reported to the relevant government agencies that deal with the preservation of cultural properties. There will then be a lengthy review to determine whether the site has historic or commemorative values that are worth protecting. No development activities are allowed at the site until the review is completed.

The Cultural Heritage Preservation Act also contains a similar procedure for renovating heritage buildings. Setting up a renewable energy system in or near a heritage building will require an impact assessment and public consultation process. A notable example of this is the installation of solar panels at the 140-year-old Hengchun Fortress in Pingtung County. Even though this project was approved by the government and did not damage the architecture of the fortress, some local residents and tourists are still put off by the highly visible solar panels.

Recently, scholars from Sweden’s Uppsala University and a compatriot architectural consultancy firm Gitter Consult AB have jointly published a study that seeks to answer two questions: When is it appropriate to deploy solar PV in a culturally significant area, where there are heritage buildings and historic streets? And how can this be done without producing too much visual impact?

The study first does not recommend installing solar panels on buildings that are shaded from the sun during most part of the day or have huge cultural and historical importance. If a building is not oriented in a way that is well exposed to sunlight, then there is no need to put solar panels on its roof. Also, some landmark structures are very recognizable and precious, so their appearances cannot be altered. Besides concerns about physical damages to the architecture, other major issues include local ordinances and visibility of solar panels to nearby residents from different vantage points.

The study contends that it is worth a try to install solar panels on a heritage building if the following conditions are met: (1) the whole structure will not be damaged or deformed in appearance due to the addition of solar panels; (2) the building has the right height and orientation for receiving sufficient sunlight; and (3) the density of the surrounding buildings is at an appropriate level that allows for the least visual impact.

The authors of the study have formulated a computerized assessment method for selecting buildings that are suitable for hosting PV systems. This method, which is derived from specially created building models, has been applied to the Swedish cities of Stockholm and Visby for determining the amount of the roof area that could be “legitimately” set aside for PV systems. Roofs that are visible from the street level and from the windows of public buildings are excluded. However, roofs that are visible from the ground level of certain private spaces (e.g., gardens and courtyards) and from the windows of residential dwellings are included.

The report states that the visibility of solar panels from the vantage points of private properties is acceptable because private spaces are not subject to the same regulations as public spaces. Furthermore, windows of residential buildings are often covered by curtains and blinds; so the visual impact can be considered negligible because it affects just a small number of observers.

The team behind the study believes that the new method that it has devised for surveying the roof area is not only highly useful for the deployment of solar PV in urban centers but can also assist in making important policy decisions. With respect to the development of the rooftop solar market in various countries, reactions of local residents to the appearance of solar panels are a crucial factor that can promote or impede growth.

Besides its obvious application in the rooftop solar market, the proposed method may also be used to address visibility issues of PV systems in other contexts that are unrelated to architecture. The author of the study have said that their modeling of buildings takes account of simple roof topographies, so the accuracy of the method decreases with more complex roof structures. Going forward, they will be focusing on improving this particular aspect.

The study, titled “Target-Based Visibility Assessment on Building Envelopes: Applications to PV and Cultural-Heritage Values,” was made available on ScienceDirect on October 8.

 (This article is an English translation of news content provided by EnergyTrend’s media partner TechNews. Photo credit: Pixabay.)

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