The Kenogami House: Energy systems in Net Zero Energy Home Design

The Kenogami Net Zero Energy off-grid houseis a virtual energy laboratory, and in constant evolution. Every system of this award-winning home is innovative from the heating and ventilation systems to the production of domestic hot water. Energy systems as advanced as this have never been seen together before, and collectively make this house in a harsh climate possibly the most efficient house ever made, evenexceeding Passive House levels of performance.

热源:一个独特的组合被动太阳能获得热量，光伏太阳能电池板，冷凝锅炉，热泵和热电池。

The ultimate goal during the design of this Net Zero Energy home was to eliminate the need for a supplementary heating system. The primary heat source is solar, stored in the heavy mass of concrete and brick, to be later released as the home cools.

However, in the Saguenay region of Quebec where this house is located, the climate is almost subarctic. Anypassive solar homein such an environment would need to be equipped with some source of supplementary heat. The Kenogami House was designed with in-floor radiant heat, orginally supplied by a condensing boiler.

由专筑网yumi，王帅编译Net Zero设计的Kenogami住宅的超级高效的建筑围护结构是如此的隔热，即使供暖系统完全失效，房子也不会降到零度以下。如果天气共同造成最寒冷的时期，再加上长期缺乏阳光，气温将不会低于10摄氏度。即使是最小的阳光和没有补充热量，这个房子也很容易保持在18°C或以上。

A heating system already being updated:

Advised by Stéphane Bilodeau, president of Enerstat group, Alain Hamel made changes so that the home runs entirely on renewable energy for all his needs bringing the home down to Net Zero Energy standards.

That is to say, the photovoltaic(PV) panels that already power his highly efficient sustainable home and part of his water heating will serve an additional purpose in the future. They will soon power a heat pump that will phase change heat to a thermal storage battery.

这样做的目的是成倍增加光伏设备产生的能量，并充分利用产生的能量，推动这种离网设计进入净零能源住宅的领域。

There are two heat pumps in this house, an air-to-air heat pump that extracts heat from outside air to heat inside air, and an air-to-water heat pump. The air to water heat pump extracts heat from ambient air inside the home and transfers it to the hot water tank, offering efficient air conditioning in summer.

As for heat storage, a thermal battery such as this can store 10 times more energy compared to an equal volume of water. It is anticipated that this system will supply all of the domestic hot water, and the entire energy needed for heating this close to net zero energy house, in the form ofin-floor radiant heat.

Radiant floor heat in a Net Zero Energy Home:

While the radiant floors were originally heated with a condensing boiler, that was since replaced by asolar thermal battery. A condensing boiler is so named because the system recovers energy from the condensation of water vapour contained in the fumes of combustion. For condensation to occur, it is essential for water to be at lower temperatures.

Condensing boilers have an efficiency rate of 95% which means that for every 100 kWh of energy supplied by the gas, 95 kWh of energy will be transformed into useful heat - which is good for a boiler, but still not as good as a heat-pump. This boiler is connected to a 'low temperature' radiant floor which operates with a water temperature of between 40 and 45°C.

The coupling of a condensing boiler with a radiant floor is in this case a particularly good match, as a condensing boiler is more effective when producing water at lower temperatures than standard radiators (65–70°C), precisely what is needed in this situation. It's difficult though to push the design of a home to Zero Net Energy if burning some kind of gas - so this high-performance home is upgraded to a solar PV powered air to water heatpump to put heat into the radiant floor heating in the slab foundation.

Heating water with PV instead of thermal solar panels:

It may seem counterintuitive at first, but there is strong case supporting the use of PV panels for heating water over thermal solar systems in Net Zero Energy homes, though recent innovations such asViessman's Vitosol solar thermal water heater重新引发了这场争论。

当最初安装时，阿兰·哈默尔的离网标准光伏系统被设计为只供应家里的电器。根据GREB(海湾生态研究小组)成员Patrick Déry后来的建议，阿兰将他的电热水器连接到他的光伏太阳能电池板，他知道这些电池板将产生比他需要的更多的能量。

电力系统将连接到电网，因此产生的任何剩余电力将反馈到电网系统。相反，当光伏板提供的电力不足时，家庭将从电网中吸取电力，希望净结果将意味着家庭是零能源。

Alain Hamel will opt for the net-metering option with Hydro-Québec; that is to say that each kWh his home feeds into the electrical grid will be deducted from his next electricity bill.

虽然不可能确定确切的供需水平，但这套系统的设计是为了满足家庭的预期消费水平，所以阿兰预计他的账单将减少到几乎0美元。从本质上讲，这就是“零能耗住宅”的概念，因为最终一切都得到了平衡。

How water is heated with PV panels in a Zero Energy Home:

In a super efficient Net Zero Energy home, and as can be seen in the diagram below, photovoltaic panels supply several types of equipment, some DC some AC.

Solar panels will first charge the 48V batteries that will then feed different receivers. The batteries then power the two heating elements contained in the hot water tank, which operate on DC 48V, the same voltage as the battery. Therefore, there is no need to go through an inverter or a chopper (which alters the type of current) during this step. Then, the current from the batteries charges a 12V battery that supplies the home with power.

The 48V batteries also supply power to outlets and home appliances that operate in AC (after passage of current through an inverter that will convert the direct current from the batteries into alternating current (120V) commonly found in homes).

And it works! After construction of this Zero Energy Home

Alain Hamel reported the following: "We have only had three to four hours of sun daily for the last four days, and the temperature of the water heater never dropped below 60°C, despite using hot water to wash dishes and clothes.This system currently provides 100% of our domestic hot water needs, and this is without skimping on usage."

Regarding winter, Alain anticipates that "the lower angle of the winter sun will increase the efficiency of the solar panels on cold, sunny days, and when the heat pump is installed this assembly should provide almost all of our needs for heat, hot water, lighting and appliances" pushing the performance to Net Zero Energy standards.

Theheat pump has a coefficient of performance (COP) of about 3,1 on average, according to Enerstat. This means that on average, for 1 kW of electrical power, the heat pump will provide 3,1 kW of thermal power for domestic hot water and heating - which certainly helps the amountof energy needed .