Table of Contents
Factors that influence the energy balance and affordability of non-residential EnerPHit projects
Does it make sense to retrofit non-residential buildings with Passive House components if the buildings have a lot of internal heat sources ?
Often, it is not possible (within reason) to retrofit buildings in compliance with the Passive House Standard for various reasons (remaining thermal bridges to the basement, suboptimal orientation, etc.). In early 2010, the Passive House Institute therefore rolled out the EnerPHit standard for retrofits using Passive House components in order to promote optimal thermal insulation standards. Since last year's Passive House Conference, certification criteria have been expanded to cover non-residential buildings.
A study [Bastian 2012] looked into whether any factors lead to different results in the energy balance of a non-residential building if the building components otherwise provide the same insulation standard as for a residential retrofit. Is it easier for an office complex to reach the EnerPHit standard (based on demand for heating energy) than for a single-family home? Do the EnerPHit requirements for building components make sense at all for non-residential buildings with very large internal heat sources, such as (inefficient) IT and communications equipment?
Methodology and subject matter
Functions to calculate variants and affordability were added to the PHPP in a parameter study to determine the influence of internal heat sources (1 to 12 W/m²) on demand for heating energy and the affordability of insulation in a hypothetical reference office building with a typical floor plan. Three statuses were compared: unrenovated, EnEV 2009 retrofit, and retrofit with EnerPHit building component requirements.
Findings and conclusion
It was found that office buildings have usage parameters that make it even easier to reach a low level of demand for heating energy after retrofits compared to residential buildings. When large office complexes are retrofitted, it generally makes sense – and pays – to strive for the Passive House Standard for new buildings, provided the old building does not present any major obstacles to low heating energy demand aside from the inevitable thermal bridges in old buildings. The EnerPHit standard is therefore especially applicable to office buildings with poor shape factors and other obstacles.
Annual benefits from a square meter of external wall insulation
(instead of the new plaster needed regardless) in the reference office building
studied with insulation qualities from each standard
and with different internal heat sources
The annual financial payback of insulation will admittedly be somewhat lower if there are great internal heat sources, but the investments nonetheless pay for themselves. With moderate internal heat sources, the EnerPHit variety always provides a better payback for the components studied than the EnEV 2009 standard does. Only when the internal heat sources reach 12 W/m² is there little difference between the two standards (Figure 1). But such high levels of internal heat are an indication that electricity is being used very inefficiently, which is also problematic in preventing overheating during the summer. Regardless of the amount of internal heat sources, Passive House and EnerPHit are optimal insulation standards for retrofits of non-residential buildings in terms of not only climate protection, but also affordability.
[Bastian 2012] Bastian, Zeno: EnerPHit-Modernisierung von Nichtwohngebäuden, insbesondere der Einfluss innerer Wärmequellen, In: Arbeitskreis kostengünstige Passivhäuser, no. 48 „Einsatz von Passivhaustechnologien bei der Modernisierung von Nichtwohngebäuden“, pp. 9-40, Passive House Institute (ed.), Darmstadt 2012.