Smart House by Kate Wilhelm

hall led to an outside door. Alexander went down that one. Near the end of this passage there were doors on both sides, one to the kitchen, one to the pantry, which he opened. Just inside the pantry was another very heavy, insulated door. A draft of cold air flowed from below when he opened this one.
    “It’s really a refrigerator,” Alexander said, leading the way down. “Gary called it a root cellar, but it’s a refrigerator.”
    It was like entering an ice cave. The room was so heavily insulated that no sound penetrated; the walls were stainless steel, the floor plastic. Bins lined one wall, shelves the other. Two fluorescent ceiling fixtures cast a bluish light. Constance shivered and hugged her arms about herself. At the far end of the room were two stainless steel carts on wheels and another door, this one only about five feet high. Charlie spotted the steel tubing; it dipped down in this room and went behind the bins.
    “Explain all this,” he said brusquely, waving at the bins, the other door, the room in general.
    “It’s Rich’s experiment,” Alexander said. “The room is a low-oxygen, high-C02 environment. Not dangerous,” he added hastily. “Fifteen percent oxygen, one percent carbon dioxide, it won’t hurt you, at least not very fast. The bins are meant to hold special produce—grapes, pears, whatever, each in its own environment most ideally suited for long keeping. The bins are airtight, and the carbon dioxide mixture is controlled by the computer.”
    Charlie reached for one of the bins, and Alexander caught his arm.
    “Don’t do that. Look.” There was a panel with symbols that meant nothing to Charlie. “That says this bin has a concentration of twelve percent carbon dioxide, and the temperature is forty-two. You don’t want to open it until you exhaust the gas, you see.”
    Charlie examined other bins with other panels, all slightly different, all containing carbon dioxide. He pointed at the end door. “And that?”
    “A dumbwaiter up to the pantry. The idea is that you can hang a side of beef down here, or bushels of fruits, stuff too heavy to lug down the stairs. So there’s a dumbwaiter.”
    Charlie was looking at him with incredulity. “I hope we can open that,” he said.
    “Oh, sure. I know what you’re thinking, Mr. Meiklejohn. I really do. But the police swarmed over this room and the bins and everything, and they couldn’t figure out a way to make it add up. Look, this bin is empty.” He pulled it open. It was about two feet deep and just as wide, narrowing at the bottom. He closed it again and went to the back of the room and opened the door to the dumbwaiter, a stainless steel box, two by three feet, about five feet high. The control here was simple: one black button for up, one for down. There was a bar handle on the outside of the door; the inside space was completely smooth without controls or handle.
    Charlie was glaring at Alexander by now. “Let’s have a look at it from upstairs,” he growled. They left the cold-storage room gladly. Constance was shivering, and Charlie felt chilled through and through. The dumbwaiter in the pantry was behind another insulated door, and there were two control buttons on the wall. Alexander started to reach for one and Charlie shook his head. “In a second.” He pulled the door open and examined the space. There were vents in the ceiling of the enclosure. He looked at Alexander questioningly.
    “A duct leads to outside. In case of a leak, you know. Carbon dioxide is heavier than air, so it wouldn’t go out the door at the top of the stairs, but it could flow into the dumbwaiter. If the dumbwaiter gets up here with any carbon dioxide inside it, it’s automatically vented out before the door will open. At least, that’s how it works when the computer’s controlling it.” He pointed to what looked like a thermometer without mercury on the side of the up and down buttons. “A safety backup sensor,” he said. “It