Home Database Adaptation options Climate proofing of buildings against excessive heat
Adaptation option

Climate proofing of buildings against excessive heat

There are several options to implement climate-proofing of buildings with respect to excessively high temperatures. Such options relate to building design (including the use of IT technologies to optimise thermal comfort) and building envelopes (roof, ceilings, external walls, doors, windows – including solar control glasses that reduce the solar radiation entering the dwelling - and foundations). Building design solutions include traditional features of dwellings located in traditionally warm climate countries, as:

  • the building aspect ratio, that is, the ratio between interior space and the external surface of the building that maximises the dispersion of internal heat and minimizes the uptake of heat through solar radiation.
  • architectonical elements such as awnings, overhangs, window shades, porticoes, white or lightly coloured external walls and roof
  • the solar orientation of the building, which can minimise the daily exposure of the building to sunlight.

Hi-tech solutions can also play a very important role. These include sensors that allow a fine monitoring of thermal conditions and hence an optimized fine-tuning of air conditioning and ventilation, and even the orientation of shading panels according to real-time insulation conditions. Sensors and digital thermal regulation devices can also be coupled with demand side management measures that help reducing the impact of cooling demand on peak loads when the electrical system is under stress (see also the adaptation option on changes in individual behaviour in the energy sector). A famous example of a building in which a complete package of state-of-the-art solutions has been applied is The Edge office building in Amsterdam; completed in 2014. The building envelope includes dynamic windows, automatic shades and displacement ventilation. A total of 28,000 sensors track movement, lighting levels, humidity and temperature, which allow an immediate and more efficient response to energy needs, such as automatically switching off heating, air conditioning and lighting in unused areas. Moreover an app provided to those working in the building allows them to adjust temperature and lighting levels around them using their smartphone. Cooling and heating involves the use of a heat exchanger that transfers heat in the desired direction between the building and an aquifer beneath it.

The organization of the space in the proximity of buildings also matters: the presence of trees in particular increases air flow and reduces the impact of solar radiation and the heat island effect typical of modern cities.

The technical features of the building envelope are crucial for its ability to control indoor temperatures. The materials of which the envelope is built and their mass in fact determine how quickly temperature differentials between indoors and outdoors are compensated. Thick-wall traditional buildings in the Mediterranean, for instance, require much less air conditioning than modern ones; alternatively, the use of materials with high thermal resistance can reduce the heat that enters the building. This option is particularly interesting for retrofitting existing building with insulation layers that compensate for the poor thermal properties of the original building materials.

Also, the use of mechanical or natural ventilation, or storing cold in materials with high thermal mass like tiles or stones, reduces the need of air-conditioning. Cold storage can be coupled with a heat pump (possibly based on a geothermal system, exploiting the differential between underground and surface temperatures) to increase the flexibility in the deployment of cold air. Adjusting indoor humidity can have a strong impact on perceived temperatures and ultimately on thermal comfort of the occupants of a building.

Roofs are also important heat exchange surfaces, and their design can help reducing significantly the energy needs of a building. Green roofs, for instance can significantly help reducing the heat island effect in cities by naturally cooling building surfaces through the action of water and vegetation. A cheaper but also effective option is painting roofs white or in light, highly reflective colours that bounce back solar radiation. Top grade white roofs reflect 80% of solar energy; black roofs on the other hand reflect only 5% to 10% (CRRC, 2013).

The described measures focus on coping with excessive heat. This does not automatically imply that all of them can also help conserving heat in winter. However, those increasing insulation of the building envelope and increasing the thermal mass can work in both ways.

Additional Details
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Adaptation Details

Category

Green

Grey

IPCC categories

Structural and physical: Ecosystem-based adaptation options, Structural and physical: Engineering and built environment options, Structural and physical: Technological options

Stakeholder participation

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.

Success and Limiting Factors

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 and Benefits

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.

Implementation Time

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.

Life Time

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

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Published in Climate-ADAPT Mar 23 2020   -   Last Modified in Climate-ADAPT Mar 23 2021

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