What kind of heat loss requirements NZEB and deep renovation sets for building envelope?

Abstract

In most of countries the energy performance of buildings is defined as (primary) energy use of whole buildingâ s (heating, cooling, ventilation, DHW, lighting, HVAC auxiliary, appliances), not as specific requirements for building envelope. For construction companies of production of modular renovation panels it in necessary to know heat loss properties of building envelope

(U, W/(m2â K); ï , W/(mâ K); ï £, W/K; q50, m3/(hâ m2)).

In this study it is analyzed what kind of heat loss requirements exists for building envelope to meet on annual basis to following targets: nZEB i.e. national nearly zero energy definition; deep energy renovation with 80 % reduction of primary energy; ZEB i.e. net Zero Energy Building = the annual primary energy use = 0 kWh/(m² a).

Indoor climate and energy calculations were made based on national energy calculation methodologies in six countries: Denmark, Estonia, Latvia, Czech Republic, Portugal, and Netherlands.

Requirements for heat loss of building envelope vary depending on requirements on indoor climate and energy performance in specific country, outdoor climate, availability of renewable energy, and building typology. The thermal transmittance of the modular wall panels for nZEB was â 5% from pre renovation thermal transmittance in Latvia, â 10% in Estonia and up to 50% in Portugal. For roof the decrease of thermal transmittance was smaller mainly due to smaller thermal transmittance before renovation.

Results show the difficulties to reach ZEB with multi-story apartment buildings in cold climate. There are not enough places to install renewables for energy production on site.