An Aggregated Embodied and Operational Energy Approach

*Shahaboddin Resalati*

## **Abstract**

Highly insulated envelopes are an integral part of any net zero energy building with a target to reduce the demand that need to be supplied by the renewable energy and other mitigating measures. While stricter insulation levels can in theory reduce the operational energy demand of buildings, the additional embodied energy investment in the insulations can become significant and not recovered within the expected timeframes. Accounting for embodied energy investment requires a paradigm shift in design of highly insulated buildings and can determine U-value levels that can be justified based on an aggregated operational and embodied energy approach. The following chapter discusses the aggregated approach in more detail showcasing the shortcomings of existing building codes and standards using a case study building. The chapter also reviews the potential barriers of adopting such approaches with a specific focus on the uncertainties of embodied energy data and offers a holistic view on its implications for various end-users and stakeholders within the construction sector. The presented analyses in this chapter depict optimal insulation levels beyond which the additional embodied energy burden cannot be recovered using the associated operational energy savings highlighting the necessity of accounting for embodied energy in developing future design principles for zero energy buildings.

**Keywords:** embodied carbon, aggregated carbon, insulation materials, optimum carbon levels, Life Cycle Assessment

## **1. Introduction**

The international building codes and standards have consistently, through their various iterations, sought to reduce the energy demand of buildings with a focus on better fabric performance and lower U-value requirement among others (**Table 1**). This was simply due to the fact that the operational energy demand, in earlier versions of standards, was taken as 10 times greater than the embodied energy load, and therefore reasonable to be given priority [2–6].

More recently however, when reducing the carbon emissions from the built environment came under more serious scrutiny, this trend that has been cemented in building standard around the world has been questioned and analysed further and different countries have started acknowledging embodied energy in their regulations. For example, France and Belgium are pioneering the move to mandate consideration of embodied energy in their building regulations in Europe. Although this is still relatively new


#### **Table 1.**

*Changes in building codes and standards around the world.*

and low impact and the building product manufacturers are only required to report Life Cycle Assessment (LCA) data should they decide to promote the environmental performance of their products, it is a significant shift towards regulating embodied energy in buildings [7]. Other countries within Europe joining the initiative include Austrian, the Netherlands and German legislations. These although acknowledge embodied energy investment a significant contributor to the overall carbon footprint of new buildings, only focus on operational energy currently. Although not fully incorporated in building regulations there exist examples of various embodied energy inventories dedicated to the construction sector and the associated materials and products including BRE's Green Guide and the Inventory of Carbon and Energy (ICE), U.S. Life Cycle Inventory Database, and the Canadian Building Material Life Cycle Inventory Database [1].

#### *An Aggregated Embodied and Operational Energy Approach DOI: http://dx.doi.org/10.5772/intechopen.103073*

#### **Figure 1.**

*Embodied to operational proportions for low and zero carbon buildings.*

In recent years, the increased use of LCA evaluations to measure the environmental performance of building materials and products has emerged from the push toward integrating embodied energy in emission equations. Various environmental certification systems have been developed and used, such as the Environmental Product Declaration (EPD) [8], to independently verify documents that transparently and accurately communicate the environmental impact of various products in accordance with EN 15804 and ISO 14025. EPDs are type III environmental declarations based on the fundamental product category rules of European standards (PCR).

Although embodied energy has been acknowledged in regulations and researched substantially in the literature, it is still not fully regulated. The ratio of embodied to operational energy has changed over the years with the operational energy reducing as a result of increased adoption of renewable energy and better fabric standards. This, at the same time, increased the use of insulation in the buildings and shifted the ratio considerably [9]. As the ratio shifts, future low and zero energy buildings may see comparable embodied and operational energy measures, or even embodied energy outweighing the operational energy (**Figure 1**), concluded in RICS [10], Kristjansdottir et al. [11], Sartori & Hestnes [12], Dixit [13], Chau et al. [14], Stephan et al. [15], Dascalaki et al. [16], Mourao et al. [17], Gustavsson & Joelsson [18], Azari and Abbasabadi [19], and Dascalaki et al. [20]. Such drastic changes necessitate a thorough examination of the constraints and challenges that come with regulating embodied energy in the construction industry.

The following section examines the relative challenges and arising opportunities, focusing on issues such as the consistency and reliability of existing data data utilised in LCA analysis, as well as inconsistent modelling methodologies that produce outputs with a high level of uncertainty, and lays the foundation for future research.
