ENERGY SAVING MEASURE #1: HERNING
HERNING is the first Social Passive Housing building in Denmark (building located for maximum sunlight / double heatflow ventilation / heavily insulated / low energy windows / geothermal system with a heating pump / hydrogen plant originally planned but cancelled due to an expensive and fragile management and maintenance).
Tenant information about heating system and tips/motivation in written form are delivered. This awareness process is supplied by direct information from local staff.
Every building is approximately consuming 14 500 kW/year for domestic hot water, ventilation, electric devices, etc.
The target group for the building induces a special context: H2O college is a university housing unit, with students tenants mean frequent transfers, some period of vacancy in the dwellings and other characteristics regarding the use of the building and its equipment
Energy data shows an unacceptable difference between highest and lowest energy consumptions among tenants inducing issues of satisfaction regarding the economic, energy and comfort performance of the building (buy factor 10). We have identified big differences of consumption levels between the dwellings. The yearly heating consumptions vary form 4 kWh/y to 1693 kWh/y (or from 0.1 kWh/m²/y to 48 kWh/m²/y).
«Soft» corrective actions need to be implemented with the tenants in order to correct these overconsumptions (tips and information). To do so, a precise knowledge of the real use of the building is needed to improve its efficiency and the tenants behaviors.
The participating Social Housing Organization has implemented a survey regarding the tenants behaviors and patterns of energy consumptions with personal interviews, online and postal questionnaires and implementation of a submetering system in dwellings in order to identify and separate energy consumptions for heating (electricity) and other personal consumptions such as computers, hi-fi, electric hardware.
ENERGY SAVING MEASURE #2: LYSTRUP
The Pilot Site include 14 houses for seniors from 1984 that have been going through a total renovation to upgrade their energy level to low-energy standards in Denmark.
The AFTER Pilot Site LYSTRUP in Denmark has been refurbished in 2011. The refurbishment as included additional insulation of the roof, walls and foundations, new energy performant windows & frames with additional sun protections, additional photovoltaics panels, and ventilation system with heat recovery. The buildings are connected to district heating.
The original building was constructed in 1984 and had a quite large energy-consumption; approximately 150kWh/M2 for room heating per year; as well as low comfort, most significant problem was not being able to sustain adequate room temperature in the coldest months.
We can’t assess the payback of the investment for the ESM, but we can say that after the implementation of the ESM the building reaches a moderate,normalized energy consumption: from 80 up to 106 kWh/sm/year. it turns out that energy consumption has highly decreased: from 41% up to 48%.
The objective of the retro-commissioning process (RCx) was to identify some weak points in the energy consumption of the building in order to improve its post-refurbishment performance.
The energy supply used by the heating coil in the ventilation is regulated by the demand for energy of the floor heating, resulting in unheated air in ventilation when floor heat is not running. The problem raised up by Aarhus is a general lack of regulation of heating system and ventilation. When the first is not working the second one doesn’t work too. So tenants complain about thermal discomfort. Through the intervention suggested there will be a separation between the heating recovering system and the underfloor heating system in order to improve the situation.
This optimization has probably not gained energy savings, if any they are quite small and cannot be exclusively identified in the metering data. The social aspects are quite good as the tenants experience a better satisfaction; less draft from ventilation.
The implementation of the ESM costs 2.984.390,00 €.
There were no technical costs related to the first optimization of the ESM, because it was done for free by the original contractor in the framework of the guarantee period
ENERGY SAVING MEASURE #3: MAARSLET
8 dwellings for the elderly people.
These buildings replaced 8 other dwellings from 1978 that was not up to todays standards and had low arcitectural value.
The new buildings respects the Energy class A2 in Denmark.
Energy – design criteria:
71 kWh/M2 pr. year (roomheating 49,4 kWh/M2 + 21,6 kWh/M2 because of legal demand for “high ventilation level”).
Yhe cost for the whole operation is approximately about 1 808 500 euro incl. Tax.
The new building is including reinforced roof insulation (445mm), and strong walls Insulation (200mm), windows & frames with triple-glazing (U=1,20 w/ m2*k incl. frame and sash), photovoltaics: solar panels on the roof 7.66 per m2. house (0.154 kW/m2 Peak power and system efficiency of 0.752).).
The systems for the building include balanced mechanical ventilation with heat recovery and by-pass function. The under floor heating is directly connected to district heating supply. A decentralized heat-exchanger is implemented for Domestic Hot Water supplied by the district heating network.
The Domestic Hot Water is a new stake in the low energy buildings as it represents an higher percentage of the global energy consumption for the building. At the time of the RCx the control-system for Domestic Hot Water was found to be adjusted quite casually. Different HDW temperatures, different flow in exchanger, even faulty valves due to dirt/foreign parts in the pipes.
The control-valve setup was adjusted for “comfort” – meaning always ”hot” and ready for production of HDW. Domestic Hot Water heat exchanger was designed to keep warm all the time. This enables DHW to be hot all time only with a small delay in temperature increase when the tenant requires DHW. The cost for this is a constant small flow of district heating. The exchanger ran idle for fast production.
The Social Housing Organization prefers the heat exchanger to be cold until the tenant (thereby saving energy in the meantime but using more water due to the delay in temperature increase requires Domestic Hot Water The setup were readjusted with the implementation of a new valve replacing the “comfort” valve (cost: 1000 EUR including hours spent) for heat-savings/no idle causing slightly longer waiting time for hot water.
For the new construction baseline data before the optimization from 1 December 2011 to 4 March 2013 are available. Heating and DHW to a net floor area (the gross floor area of the new low energy building (“new LEB”) accounts for 571 m².) of 520 m², the average consumption for this period accounted for 0.31 kWh/(m²d).
In the reporting period (after optimisation) from 4 March 2013 to 28 February 2014 the heating and DHW consumption accounted for 45.8 MWh, approx. 89.1 kWh/(m²a) resp. 0.24 kWh/(m²d). The average consumption in the reporting period (after the optimisation) is considerably lower than in total baseline period (before optimisation).