Climate proofing of buildings against excessive heat

The characteristics of a building, including the way it prevents excessive indoor heating, are usually a private contractual matter between the builder and the buyers of the building. Stakeholder participation can be relevant in case of large public buildings, in case the costs of the proposed design is significantly higher from those of a standard building and this can generate worries about the impact on public budgets, and/or about the ability of the proponent to find adequate funding for the project. Among the options mentioned, creating green areas in the vicinity of buildings to provide shading is of course subject to the usual authorization process, and requires consultation with the local communities about the preference of this option over alternative uses of the same area.

The main obstacles to climate-proof building design are economic and cultural. Some of the option proposed (higher quality material for building envelopes, green roofs, automated window shading) are more expensive and more difficult to implement and maintain than standard building practices. Culturally, architects may perceive their creativity reduced by the complexity of some of these solutions. Designing a building with total freedom of choice as to shapes and materials, while relying on air-conditioning to take care of indoor thermal comfort is a tempting perspective that reduces technical challenges, building costs and increases the aesthetic range for design options. This is particularly relevant for large building units such as skyscrapers, malls, campuses etc. The relevance of this obstacle is likely to fall in the coming years as climate-proofing solutions reach technological maturity and technological innovation will drive down their costs. However, there is no guarantee that the flexibility in building design currently offered by air-conditioning will ever be equalled by these solutions.

On the other hand, particularly for smaller units such as single-family homes or small-medium sized residential neighbourhoods, climate-proofing can prove a very stimulating design challenge. There are a number of initiatives in the EU implementing green solutions for residential buildings and urban planning, including greening of urban landscapes, awareness raising campaigns and financial incentives. Examples of financial incentives are: subsidy to green roofs of 30 euro per m² with at least covering of 40 m² in Rotterdam (the Netherlands), subsidies for private owners of green roofs foreseen by the Hamburg’s Green Roof Strategy, up to 60% of building costs; or the incentives for thermal insulation of buildings envelope in Italy which can cover up to 65% of the cost of the insulating materials and of their installation.

Costs vary according to the solution applied and the location where they are implemented. For example, green roofs in Germany cost about 77 to 145 Euro per square meter, and 145 to 242 Euros in the US, due to the different maturity of the industry and local building characteristics. According to the Hamburg’s Green Roof Strategy case study “estimated costs for installation, maintenance and replacement over a period of 40 years cumulate to € 20.500 for 300 square meters surface both for grey and green roofs. When focusing only on the initial installation, a green roof costs € 9.500 versus € 3.000 for a grey roof for 300 square meters surface”.

White roofs are significantly less expensive, with a price tag per square meter of about 6.5-9.8 Euro, according to an American cost comparison website. Wall and roof insulation prices vary widely according the insulating material, but usually range between 40 and 100 Euro per square meter. Solar control glasses’ prices are comparable or marginally higher than standard insulating glasses commonly installed in European homes’ windows. Packing a full menu of state-of-the-art climate-proofing solutions into a building can be costly, and it is easier to do it from scratch by designing a new building to that purpose. The extremely energy efficient and thermally comfortable 39,673 m² of office space (plus 11,558 m² of indoor parking space) of The Edge building required an investment of 74 million Euro (total building costs).

These costs must be weighed against the beneficial impacts on households, firms and public administrations budgets in terms of energy savings, which for state-of-the-art solutions can be very substantial and even result in near-zero net energy use. The increase of green spaces in an urban context brings about also a number of co-benefits in terms of improved health, urban biodiversity, social interactions, and aesthetic improvements.

At the regulatory level, the technical solutions mentioned above can be incorporated into building codes. When this is not already enforced, a regulatory move in this direction is advisable for EU countries with a warm climate.

The revised Energy Performance in Buildings Directive requires that all new public buildings to be N-ZEB (Near Zero Energy Buildings) since 2018 and that the whole European building stock to be N-ZEB by 2050. Although not directly targeting adaptation to high temperatures, these requirements will call for a widespread application of the measures here described.

The implementation time varies according to the type of intervention, ranging from a few hours to install curtains and shades to several months or even years to design and build a climate-proof building from scratch.

Lifetime varies with the type of intervention, ranging from few years to the residual lifetime of the building.